PEDOT: PSS Doped Activated Biochar as a Novel Composite Material for Photocatalytic and Efficient Energy Storage Application

Abstract

Herein, we report the synthesis of activated biochar from green algae and the effect of its doping on the structural, photocatalytic, and energy storage properties of PEDOT-PSS. The morphology of pure and doped samples was investigated with Fourier Transform Infrared Spectroscopy (FTIR), Atomic Force Microscopy (AFM), Brunauer–Emmett–Teller (BET) analysis, and thermogravimetric analysis (TGA). AFM results for PEDOT-PSS@6wt.% of BC indicate that the calculated average peak height, particle size, and roughness were 283 nm, 136 nm, and 71 nm, respectively. Adding biochar to PEDOT-PSS significantly improved the thermal stability of PEDOT-PSS up to 550 °C. The novel photocatalyst PEDOT-PSS@6wt.% BC improved photocatalytic performance by approximately 17% in Methylene Blue (MB) dye removal. The electrochemical performance in terms of supercapacitors for the synthesized samples was investigated using cyclic voltammetry (CV), galvanostatic charge–discharge (GCD), specific capacitance, stability, and electrochemical impedance spectra (EIS). PEDOT-PSS@6wt.% of BC as a novel electrode material in supercapacitors exhibits an initial specific capacitance of 1300 Fg⁻¹. Moreover, the PEDOT-PSS@6wt.% of BC electrode shows excellent stability up to 1000 cycles of operation. The EIS studies suggest the presence of charge transfer resistance. Considering the economical biosynthesis and multifunctional features, the PEDOT-PSS@6wt.% of BC could potentially be used as a photocatalyst to remove organic dyes and supercapacitors in energy storage applications.

1. Introduction

In the recent past, supercapacitors have emerged as highly efficient energy storage devices in modern technological applications due to their high-power capacities, fast charge–discharge ability, long-term stability in terms of cycle life, and high coulombic efficiency [1]. Generally, supercapacitors are classified as electrochemical double-layer capacitors (EDLCs) or pseudo capacitors depending on their capacitive behavior [2,3]. In the case of an EDLC, it stores energy through the adsorption of electrolyte ions on the electrode surface through an electrostatic process. On the other hand, a pseudo capacitor generally stores the energy through a reversible faradaic redox reaction with an electrolyte on the surface of the electrode [4,5]. In recent years, most of the commercially used supercapacitors have been developed using an EDLC, as they have remarkable stability with extremely high operations of charge–discharge cycles [6,7].

Very recently, due to growing urbanization and industrialization, the water contaminants in various natural resources have increased exponentially [8]. An increase in water contaminants leads to a decrease in the quality of drinking water [9]. The major contaminants present in the water include organic molecules, various dyes, toxic metal ions, and compounds containing carcinogenic and mutagenic molecules [10,11]. To address this issue of wastewater treatment, several methods have evolved recently, with some advantages and limitations. Great progress has been achieved in the field of carbonaceous materials for environmental protection [12]. These novel materials are highly efficient in pollution control, including wastewater treatment. Due to their minimal cost, great efficiency, simple synthesis, and easily available raw material, biochar-based photocatalysts for water treatment against various organic dyes have drawn significant attention from researchers around the world [13].

Poly(3,4-ethylenedioxythiophene) doped with polystyrene sulfonate, PEDOT-PSS, is a conducting polymer with remarkable properties that make it a versatile material in various fields, including solar cell and energy applications [14]. PEDOT-PSS exhibits high electrical conductivity, transparency, and excellent stability, making it an attractive candidate for improving the performance and efficiency of solar cells and energy storage devices [15]. The doping of PEDOT-PSS improves its structural properties by introducing dopant molecules into the polymer matrix, leading to changes in its structural configuration and electrical properties [16]. When PEDOT-PSS is doped, it can experience structural modifications such as increased crystallinity, improved chain alignment, and enhanced intermolecular interactions [17]. These changes can result in improved charge transport properties, higher conductivity, and better mechanical stability of the polymer [18].

In the last decade, highly porous carbon-based materials such as carbon nanotubes, graphene carbon fullerenes, and activated biochar have been used extensively for preparing electrodes for EDLC [19]. These carbon-based materials generally have a high specific surface area for the adsorption of electrolytic ions with good chemical stability [19]. Apart from that, these carbon materials facilitate the ease of adsorption of electrolytes at the surface and provide a good number of active sites for chemical reactions [20]. These features make them a potential candidate for the fabrication of EDCL electrodes. Carbon is abundantly available as a natural raw material, thereby reducing the cost of production [20].

Biochar, a carbon-rich material derived from biomass pyrolysis, can serve as a dopant to enhance the properties of conducting polymers [21]. Biochar doping can improve the photocatalytic activity of conducting polymers by extending light absorption into the visible range, enhancing charge separation and transfer, and increasing the surface area for catalytic reactions. Additionally, biochar’s porous structure can provide greater surface area for ion storage, further improving the supercapacitor performance [22]. Overall, doping conducting polymers with biochar can be important for optimizing the performance of these materials in photocatalysis and supercapacitors by tailoring their properties to meet specific application requirements.

Biochar enhances thermal conductivity and light absorption when integrated into polymer matrices, significantly improving the performance of phase change materials (PCMs) used in solar energy applications. For instance, a study demonstrated that biochar-embedded PCMs achieved a thermal conductivity of 0.49 W/m⋅K, enhancing energy storage capabilities essential for photovoltaic systems [23]. Additionally, biochar’s high surface area and electrical conductivity make it a promising alternative to traditional fillers in polymer composites, potentially leading to improved mechanical and electrical properties [24]. Furthermore, biochar’s role as a photocatalyst support enhances solar fuel generation by improving charge separation and reducing electron-hole recombination, which is crucial for efficient energy conversion. PEDOT-PSS has been studied extensively for its unique properties. Jing et al. investigated the photoinduced cathodic protection performance of a ZnO/PEDOT-PSS electrode [23]. Their research shows that PEDOT: PSS addition enhances the charge transfer, resulting in a larger positive photo potential and photocurrent. Liu et al. focused on the conductivity measurements of PEDOT-PSS electrodes. They proposed a photo-polymerizable additive that improves the conductivity of PEDOT-PSS electrodes and enables photo-patternability. Highly conductive PEDOT-PSS electrodes with various patterns are applied in flexible perovskite light-emitting diodes [24]. A combined mathematical approach was used by Hong et al. to evaluate the photoelectrical performances of PEDOT-PSS. The proposed algorithm provides simulations of the characteristics of innovative nanomaterials based on PEDOT-PSS, such as zinc oxide nanorod (ZnO NR) hybrid structures [25].

Our research aims to create a new composite made from sustainable materials for supercapacitors and photocatalytic applications. PEDOT-PSS doped with 3 wt.% and 6 wt.% of activated biochar was investigated. The morphological, photocatalytic, and cyclic voltammetry measurements were investigated. The novel combination of biochar and PEDOTPSS in photocatalytic and battery applications offers several unique benefits. Biochar, a type of charcoal produced from organic materials, is known for its high porosity and large surface area, which allows for the efficient adsorption of contaminants in water and air. When combined with PEDOTPSS, a conductive polymer, the resulting hybrid material exhibits enhanced conductivity and stability, making it ideal for use in both photocatalytic and battery applications. Additionally, the utilization of biochar and PEDOTPSS in tandem can improve the overall efficiency and performance of such systems, leading to more sustainable and cost-effective solutions for environmental remediation and energy storage. We believe that the unique combination of these two materials with distinct properties and advantages (PEDOT-PSS and activated biochar) will improve charge transport and conductivity in energy and photocatalytic applications.

2. Results and Discussion

2.1. Synthesis of PEDOT-PSS, Activated Biochar, and BC-Doped PEDOT-PSS

To prepare PEDOT-PSS, 3,4-Ethylenedioxythiophene (EDOT), Poly(styrene sulfonate) (PSS) and dimethyl sulfoxide were purchased from Sigma Aldrich. First, 10 mg of PSS was dissolved in dimethyl sulfoxide to make a 10 mg PSSH (poly (styrene sulfonate)) solution. To this solution of PSSH, the EDOT monomer was added. Further, an oxidizing agent like ammonium persulfate (APS) was added to the solution. The oxidant helps in the polymerization of EDOT. The solution was stirred at room temperature for 6 h. to allow the polymerization of EDOT and the formation of PEDOT chains within the PSS matrix. Finally, after the completion of polymerization, the PEDOT-PSS could be precipitated and washed.

The green algae was rinsed with distilled water and air-dried at room temperature. Once dry, the green algae was finely ground into a powder. The powder was then subjected to pyrolysis in a tube furnace for 4 h to produce biochar. The flow rate of nitrogen gas was set at 50 mL per minute and the furnace temperature was maintained at 400 °C [14]. Further, 10 g of algae biochar powder was added to 100 mL of 5M KOH in a reflux setup. The mixture was refluxed for 5 h at a temperature of 80 °C with a stirring speed of 150 rpm to produce activated biochar for the composite preparation.

To prepare the PEDOT-PSS@3wt.% biochar composite, 0.97 g of PEDOT-PSS and 0.03 g of activated biochar were dissolved in water using magnetic stirring for approximately 2 h. The solution was then left in a Petri dish to dry in an oven to obtain the desired sample. For a 6 wt.% doping, the same procedure was repeated using 0.94 g of PEDOT-PSS and 0.06 g of activated biochar.

Table 1. The sample preparation condition.

Sample	PEDOT:PSS in gm	Activated Biochar in gm	Water in mL
PEDOT-PSS@3wt.% BC	0.97	0.03	50
PEDOT-PSS@6wt.% BC	0.94	0.06	50

shows the compositions of all the prepared samples.

2.2. Material Characterization Techniques

The chemical features of the synthesized samples in terms of functional groups of the samples were investigated using FTIR (Shimadzu, Tokyo, Japan, FT-IR 8400S Spectrophotometer) in the spectral range of 500–4000 cm⁻¹. An atomic force microscope (AFM-Model No. NT-MDT) was used to investigate the surface features of the samples, such as surface topography, surface roughness, and grain size. The thermal stability of the samples was investigated through thermogravimetric analysis using a thermal analyzer (TGA-Shimadzu, Tokyo, Japan, TGA-50) in the temperature range 50–700 °C, with a ramping rate of 10 °C/min until 700 °C, with a nitrogen flow rate of 20 mL min⁻¹. A Nova 2200 e pore analyzer and surface area analyzer (Quantichrome Instruments, Beijing, China) was used for BET analysis of the samples. The electrodes using prepared samples were tested for their electrochemical performance through cyclic voltammetry (CV) and galvanostatic charging and discharging (GCD) using the electrochemical workstation (Chenhua, Shanghai, China, CHI 660 °C) at a rate of 0.002 V/s in the range of −0.1 to 1.2 V. All the electrochemical investigations were carried out using a three-electrode system with PEDOT-PSS@ BC as the working electrode, Pt wire as the counter electrode, and Ag/AgCl as the reference electrode in a electrolytic solution of 1M LiPF6.

2.3. FTIR Analysis

FTIR spectroscopy is a valuable analytical technique that could be used in identifying and confirming the presence of biochar doping within PEDOT-PSS composites based on the distinctive spectral features and changes observed in the FTIR spectrum. Figure 1 shows FTIR spectra for PEDOT-PSS and PEDOT-PSS doped with 6 wt.% BC. The three characteristic peaks that appeared due to BC doping are a peak at around 2950 cm⁻¹ indicating C-H stretching vibrations, a peak at 1680 cm⁻¹ confirming the presence of C=O stretching vibrations for carbonyl groups, and finally a peak at around 780 cm⁻¹ showing C-H bending vibrations. These peaks can give insight into the functional groups present in the activated biochar [26,27,28]. These organic functionalities can promote improved charge transfer kinetics in the composite material, enhancing the efficiency of charge transport processes in both photocatalytic and supercapacitor applications. Enhanced charge transport can lead to better photocatalytic activity and higher performance in supercapacitors.

2.4. AFM Analysis

Atomic Force Microscopy (AFM) is a powerful tool for imaging surfaces at the atomic scale and characterizing surface properties such as roughness and particle size. Figure 2 shows the AFM image and histogram for the size of the particle for PEDOT-PSS doped with 6 wt.% BC. We can see from the AFM image the presence of peaks and valleys on the surface of our novel sample. This can increase the effective surface area of the material. This surface structure could be more active for catalytic reactions, leading to enhanced efficiency in light absorption and catalytic activity [29]. The calculated average peak height, particle size, and roughness were 283 nm, 136 nm, and 71 nm, respectively. The obtained calculated parameters could be an important factor for increasing the reaction kinetics and surface reactivity in different applications.

2.5. BET Analysis

Our targeted sample (PEDOT-PSS @ 6 wt.% BC) was subjected to degassing at 80 °C for a duration of 8 h. The BET surface analysis showed a value of 422 m²/g. The cumulative surface pore volume was measured to be 0.0912 mL/g. In addition, the pore diameter was found to be 46.56 A°, which suggests relatively high pore space within the investigated doped sample. A high surface area provides more active sites for chemical reactions in photocatalysis and enhances the electrode–material interface in supercapacitors, potentially leading to improved performance. Similarly, the measured cumulative surface pore volume of 0.0912 mL/g suggests the presence of pores that can facilitate ion transport and storage in supercapacitors [30]. Overall, these values are promising and could contribute to the effectiveness of the material in both photocatalyst and supercapacitor applications.

2.6. TGA Analysis

Thermal gravimetric analysis, TGA, is a valuable analytical technique that can help researchers and engineers evaluate the suitability of materials for use in photocatalytic and supercapacitor applications. Figure 3 illustrates the TGA analysis for PEDOT-PSS and PEDOT-PSS@6wt.% BC. Both the samples, pure and doped, exhibited a similar nature of weight loss at the observed temperature, with the doped sample having more thermal stability than the pure one. As observed from the figure, the doped sample exhibited greater thermal stability compared to the undoped sample at up to 600 °C. Three distinct weight losses could be observed: at 150 °C, the weight losses of PEDOT-PSS and PEDOT-PSS@6wt.% BC were 14% and 11%, respectively. At 250 °C, the weight losses were 7% and 5% for PEDOT-PSS and PEDOT-PSS@6wt.% BC. Finally, at 350 °C, the weight losses were 21% and 19% for PEDOT-PSS and PEDOT-PSS@6wt.% BC. The activated biochar was thermally more stable compared to both these samples, and the TGA profile of activated BC was reported in our earlier studies [26]. Hence, the addition of activated BC has a significant effect in improving the thermal stability of PEDOT-PSS.

For photocatalytic applications, improved thermal stability can ensure that the material maintains its catalytic activity for longer periods, even under high-temperature conditions. This can result in enhanced performance and durability of the photocatalyst, making it more effective in various environmental remediation and energy conversion processes [31,32]. In the case of supercapacitor applications, increased thermal stability can help prevent degradation of the electrode material and electrolyte, leading to a more reliable and long-lasting supercapacitor device. Furthermore, the enhanced thermal stability can also contribute to the safety of the supercapacitor by reducing the risk of thermal runaway and failure under extreme conditions.

2.7. Photocatalytic Properties

The combination of PEDOT-PSS and activated biochar is a novel approach to material design for photocatalytic applications. This unique composite offers a new platform for exploring the synergistic effects between organic conductive polymers and biochar, opening up possibilities for developing advanced photocatalytic materials with improved performance. The absorbance spectrum of UV–visible light was studied in the range of 300–1200 nm, as shown in Figure 4. A typical exciton absorption peak at 390 nm was observed in the absorbance spectrum of our investigated samples [33]. As we can see, there was a noticeable increase in light absorption as a result of activated biochar doping. The reason for this increase in light absorption in PEDOT-PSS, when doped with activated biochar, is due to the presence of additional active sites and the enhanced surface area provided by the biochar. Activated biochar is known for its high porosity and large surface area, which can effectively trap and scatter light, ultimately leading to increased light absorption by the composite material.

The photocatalytic activities of PEDOT-PSS, PEDOT-PSS@3wt.% BC, and PEDOT-PSS@6wt.% BC were evaluated under optimal conditions for removing Methylene Blue (MB) dyes. The changes in the UV–vis absorption spectra of MB before and after stirring with PEDOT-PSS, PEDOT-PSS@3wt.% BC, and PEDOT-PSS@6wt.% BC were analyzed as shown in Figure 5a–c, respectively. As the exposure time increased up to 240 min, MB exhibited a maximum absorption band at 680 nm which gradually decreased in intensity, resulting in the discoloration of the solution. The photodegradation of the dye molecules may also influence the absorption band of MB at 680 nm under the influence of light. As the exposure time increases, the photodegradation process may decrease the concentration of MB molecules in the solution, resulting in a decrease in the intensity of the absorption band at 680 nm.

Photodegradation (PD) activity is investigated by measuring the absorbance of the dye solution at 680 nm. The following relation is used to calculate the effectiveness of dye’s photodegradation in aqueous solution [34].

$$PD\%={\displaystyle \frac{(C_o-C_t)}{C_o}}\%$$

(1)

After the completion of the photocatalytic degradation process, the initial and final concentrations of the dye (C_o and C_t) were calculated. In a standard experimental procedure, 50 mL of dye solution was mixed with 25 mg of synthesized samples. Figure 6 illustrates the variation in MB decomposition efficiency with irradiation time for PEDOT-PSS, PEDOT-PSS@3wt.% BC, and PEDOT-PSS@6wt.% BC. It is evident from the figure that the decomposition efficiency of PEDOT-PSS increases with the incorporation of biochar activated through doping and irradiation time. The irradiation process can result in the creation of more active sites on the biochar surface, effectively increasing its surface area. This, in turn, provides more opportunities for PEDOT-PSS to interact with the biochar, ultimately enhancing the decomposition efficiency.

The response kinematics of MB dye degradation and the rate constant value (k) were analyzed using the relation mentioned below.

$$ln \left({\displaystyle \frac{C_t}{C_o}}\right)=-k{K}_t=-k_{app}t$$

(2)

where K, k, and k_app correspond to the adsorption equilibrium constant, degradation rate constant, and the apparent rate kinetic constant, respectively. Figure 7 illustrates the dependence of ln (C_t/C_o) and dyes’ irradiation times. A linear behavior observed in the plot indicates that the degradation kinetics of MB dye follow pseudo-first-order kinetics. The value of k_app was determined from the slope and was found to be 0.00805 min⁻¹. ln (C_t − C_o) values for PEDOT-PSS increased with activated biochar doping when studied over irradiation time for MB, which suggests that the degradation efficiency of MB is enhanced in the presence of activated biochar. Activated biochar can enhance the transfer of electrons, which may contribute to the degradation of MB through various oxidative processes.

The overall photocatalytic performance of PEDOT-PSS doped with 6 wt.% BC showed excellent results; it was also observed that the presence of BC makes a significant contribution towards the photocatalytic degradation of MB. PEDOT-PSS is an excellent hole-transport-conducting polymer due to the superior charge separation between PEDOT and PSS, which facilitates the charge mitigation among the polymer backbone, resulting in the improved photocatalytic degradation of MB. Furthermore, the presence of activated BC acts a protective layer and facilitates charge carrier e/h recombination at the electrode surface. This e/h recombination at the surface generates excessive charge carrier transport and supports enhanced catalytical reactions. Hence, this study reveals that PEDOT-PSS modified with small concentrations of activated BC could be a potential way of fabricating new-generation photocatalytic materials for the effective removal of aqueous dyes and, in particular, MB.

2.8. Electrochemical Properties

One of the most popular techniques for understanding the electrochemical characteristics of supercapacitors is cyclic voltammetry (CV), which can provide important insights into the behavior of various types of SCs. The electrochemical properties of bare PEDOT-PSS and PEDOT-PSS@3wt.% BC- and PEDOT-PSS@6wt.% BC-modified electrodes were investigated using cyclic voltammetry (CV) using a three-electrode system. The CV curves for PEDOT-PSS and PEDOT-PSS @ 3 wt.% BC- and PEDOT-PSS@6wt.% BC-modified electrodes analyzed in a potential window of −0.4–1.2 V at a scan rate of 100 mVs⁻¹ are depicted in Figure 8. The CV curves for all the samples indicate pseudocapacitive behavior as a result of Faradaic reactions on the electrode surface. The CV curves of the sample show the presence of a broad redox peak with small separations rather than the quasi-rectangular curve normally displayed by electric double-layer capacitors. The presence of a broad redox peak in the CV curves of the sample indicates a reduction in pseudocapacitive nature. The superior specific capacitance of PEDOT-PSS@6wt.% BC electrodes is demonstrated by the area under the curve, which increases with increasing BC concentrations in PEDOT-PSS. The enhanced CV performance of PEDOT-PSS@6wt.% BC electrodes may be attributed to the porous structure of PEDOT-PSS@6wt.% BC, as well as the active sites and better electrolyte diffusion in the electrode surface provided by BC in PEDOT-PSS [35,36]. Furthermore, a large surface area for quick electron transport is made possible by the activated biochar present on the PEDOT-PSS electrode surface.

Using the GCD approach at a constant current density of 1 A/g, the specific capacitance for PEDOT-PSS, PEDOT-PSS@3wt.% BC, and PEDOT-PSS@6wt.% BC electrodes was examined and is displayed in Figure 9. The charge–discharge curve’s nonlinear and asymmetric response reveals the samples’ pseudocapacitive nature. When compared to pure PEDOT-PSS, PEDOT-PSS@6wt.% BC exhibits a longer discharge time, indicating a very small solid–liquid interface resistance, minimal energy loss, and greater capacitance values for the modified electrode.

Figure 10 represents the specific capacitance values (C_sp) for bare PEDOT-PSS, PEDOT-PSS@3wt.% BC, and PEDOT-PSS@6wt.% BC. One can notice from the plots that the C_sp values for PEDOT-PSS@6wt.% BC are significantly higher than those of bare PEDOT-PSS and PEDOT-PSS@3wt.% BC at a constant current density of 1 A/g (1123 F/g for PEDOT-PSS v/s 1328 F/g for PEDOT-PSS@6wt.% BC). These enhanced C_sp values support the observations drawn from the GCD curves. The improved specific capacitance in the case of PEDOT-PSS@6wt.% BC could be due to (i) improved electrochemical interactions between the PEDOT-PSS and activated BC, (ii) the improved diffusion of electrolytic ions at the interface between activated BC and PEDOT-PSS, (iii) the enhanced specific surface area for the electrochemical interactions at the electrode, (iv) the increased number of active sites for electrochemical interactions due the activated BC presence, and (v) the activated BC in PEDOT-PSS facilitating the reaction kinetics and reaction rate. Further, the BC acts as a protective layer and facilitates the migration of charge carriers in the PEDOT-PSS matrix. Both specific capacitance and coulombic efficiency show an excellent retention of capacitance for 1000 cycles of charge–discharge operation, as shown in Figure 11, indicating the long-term stability of PEDOT-PSS@6wt.% BC.

Furthermore, electrochemical impedance spectroscopy was used to investigate the charge transfer resistance in the case of bare PEDOT-PSS, PEDOT-PSS@3wt.% BC, and PEDOT-PSS@6wt.% BC electrodes; this is represented in Figure 12. In the Nyquist plots, the semi-circular nature of the arc radius represents the transportation of charge carriers at the interfacial layers and electron transfer resistance. It can be seen from the Nyquist plots that the arc radius for the PEDOT-PSS@6wt.% BC sample is much smaller than that of bare PEDOT-PSS as well as that of PEDOT-PSS@3wt.% BC, indicating an enhancement in the transportation of charge carriers at the interfacial surface. The presence of activated BC in PEDOT-PSS significantly reduces the resistance of PEDOT-PSS at the electrode surface and facilitates charge carrier transport.

Biochar is known for its high thermal stability, which helps to enhance the overall stability of the hybrid material when subjected to high temperatures. Additionally, the presence of biochar in the composite material can act as a reinforcing agent, improving the mechanical properties and reducing weight loss during thermal degradation. Furthermore, the large surface area and high porosity of biochar can provide more active sites for photocatalytic reactions, leading to increased photocatalytic activity. Finally, the conductive nature of biochar can improve the overall conductivity of the material, leading to enhanced electrochemical performance in battery applications. Overall, the synergistic effects of biochar and PEDOTPSS result in a composite material with improved thermal stability, enhanced functional properties, and better overall performance in various applications.

3. Conclusions

Improving the properties of conducting polymer composites is of great interest in various applications due to their unique properties. We have carried out a systematic study to enhance UV absorption and cyclic voltammetry properties of PEDOT-PSS by incorporating activated biochar (BC) at different concentrations. The average peak height, particle size, and roughness were 283 nm, 136 nm, and 71 nm, respectively, as recorded from AFM. The calculated parameters could be an important factor for increasing the reaction kinetics and surface reactivity in different applications. The analysis of structural changes using AFM and FTIR shows an improvement in crystallinity and crystallite growth, with a noticeable change at 6 wt.% doping. C-H and C=O stretching vibrations were confirmed by FTIR investigation. The doping of activated biochar in PEDOT-PSS significantly enhances the photocatalytic activity and improves MB dye removal. Further, the PEDOT-PSS@6wt.% BC composite shows excellent electrochemical performance in CV, GCD, and specific capacitance. The electrode fabricated using PEDOT-PSS@6wt.% BC composite showed excellent long-term stability. The EIS studies showed that the arc radius for the PEDOT-PSS@6wt.% BC sample was smaller than that of bare PEDOT-PSS or PEDOT-PSS@3wt.% BC, indicating an improvement in the transportation of charge carriers at the interfacial surface. The presence of activated BC in PEDOT-PSS significantly reduced the resistance of PEDOT-PSS at the electrode surface and facilitated charge carrier transport. Owing to simple and low-cost synthesis, and excellent photo catalytical and electrochemical properties, these activated biochar-doped PEDOT-PSS composites could be a potential multifunctional material for water treatment and energy storage applications.