Abstract
In this study, biosynthesized α-MnO2/NiO NPs and chemically oxidative polyaniline (PANI) were synthesized to form ternary composite anode material for MFC. The synthesized materials were characterized with different materials (UV-Vis, FTIR, XRD, TGA-DTA-DSC, SEM-EDX-Gwyddion, CV, and EIS) to deeply examine their optical, structural, morphological, thermal, roughness, and electrocatalytic properties. The degree of surface roughness for α-MnO2/NiO/PANI was23.65±5.652 nm. This value was higher than the pure α-MnO2, pure PANI, and even α-MnO2/PANI nanocomposite due to surface modification. The total charge storing performance for bare PGE, α-MnO2/PGE, PANI/PGE, α-MnO2/PANI/PGE, and α-MnO2/NiO/PANI/PGE were 5.291, 17.267, 20.659, 23.258, and 24.456 mC. From this, the charge storing performance formed by α-MnO2/NiO/PANI-modified PGE was highest, indicating that this electrode is best in cycle stability and increases its life cycle during energy conversion time in MFC. This is also supported by its effective surface area, having a value of 0.00984 cm2. From this, it is evidenced that the ternary composite catalyst-modified anode facilitates the fast electrocatalytic activity as observed from its high peak current and lower peak-to-peak potential separation (ΔEp=0.216 V) than other electrodes. Such surface modification helps to store more electrical charge by increasing electrical conductivity during its charge/discharge processing time. In addition, the lower charge transfer resistance property with a value of 788.9 Ω and the fast heterogeneous electron transfer rate of ~2.92 s-1 enable to facilitate glucose oxidation, and this enhances to produce high power output and increase wastewater treatment efficiency. As a result, the bioelectrical activity of α-MnO2/NiO/PANI composite-modified PGE was very effective in producing a maximum power density of 506.96 mW m-2 with COD of 81.92%. The above observations justified that α-MnO2/NiO/PANI/PGE serves as an effective anode material in double-chambered MFC application.
Highlights
Focusing on alternative, renewable, and carbon-neutral energy sources produced by the bioelectrochemical system is necessary to keep the environment from pollution and economic sustainability across the globe [1]
In pure α-MnO2, the absorption peak observed at about 285 nm might be an electronic transition from the O2p valence band to the Mn3d conduction band or from the triply degenerate (t2g) valence band to the doubly degenerate conduction band if the shape is purely tetrahedral, as shown in Figure 2(a) [22]
2 3.64 1.18 0.77 0.87 100 (e) where Ipa is the anodic peak current (A), n is the number of electron transfer, D is the diffusion coefficient of HPO24− (7:60 × 10−6 cm2/s [49]), v is the scanning rate (V s-1), A is the effective electroactive area (m2), and C is concentration of phosphate-buffered solution (PBS). Their effective areas were described to be 0.00269, 0.00695, 0.00945, 0.00942, and 0.00984 cm2 for unmodified pencil graphite electrode (PGE), α-MnO2/PGE, PANI/PGE, α-MnO2/PANI/PGE, and α-MnO2/NiO/PANI/PGE, respectively. These results suggest that α-MnO2/NiO/PANI nanocompositemodified PGE has the largest effective surface area which helps to facilitate a fast electrocatalytic activity as observed from its high peak current
Summary
Renewable, and carbon-neutral energy sources produced by the bioelectrochemical system is necessary to keep the environment from pollution and economic sustainability across the globe [1]. The low power output, poor stability, and cost-ineffectiveness to upgrade the device are the main drawbacks that affect MFC [2] This is due to the low electron transfer rate and low EAM attachment found on electrode components [5]. Electrodes from conventional carbon materials are the most common but are poor in energy conversion and low in wastewater treatment efficiency due to the short-term stability results for sluggish electron transfer rates between electrodes and EAM [6]. This limitation in general affects the whole performance of MFC
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