Increase In Electron Transfer Rate Research Articles

Enhanced Catalytic Activity of CuO@CuS Core–Shell Structure for Highly Efficient HER Application

Using electrocatalytic water reduction to produce hydrogen fuel offers significant potential for clean energy, yet its large-scale adoption depends on developing cost-effective, non-precious, and efficient catalysts to replace expensive Pt-based state-of-the-art HER catalysts. The catalytic HER performance of an active catalyst largely depends on the available catalytic active sites, conductivity, and intrinsic electrochemical kinetics, all of which can be altered by incorporating a heteroatom into the active catalyst structure. Herein, we synthesized a unique nitrogen-doped CuO@CuS (NCOS) core–shell-structured catalyst through a facile hydrothermal process followed by an efficacious nitrogenation process, and its electrochemical performance for the HER was systematically analyzed. The NCOS core–shell-structured catalyst exhibits a reduced overpotential (55 mV) and Tafel slope (107 mV dec−1) compared to the pure CuS (CS; 179 mV and 201 mV dec−1) catalyst at a current density of 10 mA cm−2. Moreover, the NCOS core–shell-structured catalyst demonstrates excellent endurance for up to 50 h of chronopotentiometric testing at a driving current density rate of 10 and 100 mA cm−2. This excellent catalytic HER activity is a result of an increased electron transfer rate and a greater number of accessible active sites, attributed to a change in structural properties and the high electronic conductivity aroused from nitrogen incorporation, as evidenced from the TOF and EIS curve analyses.

Synthesis of composite films for ZnO-based memristors with superior stability

Memristors have unique non-volatile characteristics that potentially can emulate biological synapses for applications in neural computing systems. However, the random formation of conductive filaments in these devices can cause various unreliability problems. In this work, films of a composite of ZnO nanoparticles and carbon nanotubes were prepared as functional layers for memristors by an in-situ growing strategy (ZnO@CNT-IS) using a straightforward high-temperature annealing treatment. This approach allowed for the formation of a high-quality films with uniform loading of ZnO nanoparticles on the carbon nanotubes, which contributed to a lower formation energy for oxygen vacancies and increased electron transfer rate. As a result, the memristors exhibited faster switching response speed, lower power consumption, and a stabilised switching ratio even after 2000 switching cycles. Based on the analog switching behaviour, the ZnO@CNT-IS-based devices showed significant biological synapse functions and plasticity, indicating their potential for high-density storage and neuromorphic computing.

Enhancement of bio-promoters on hexavalent chromium inhibited sulfur-driven denitrification: repairing damage, accelerating electron transfer, and reshaping microbial collaboration

Proposing recovery strategies to recover heavy-metal-inhibited sulfur-driven denitrification, as well as disclosing recovery mechanisms, can provide technical support for the stable operation of bio-systems. This study proposed an effective bio-promoter (mediator-promoter composed of L-cysteine, biotin, cytokinin, and anthraquinone-2,6-disulfonate) to recover Cr(VI) inhibited sulfur-driven denitrification, which effectively reduced the recovery time of NO3–-N reduction (18–21 cycles) and NO2–-N reduction (27–42 cycles) compared with self-recovery. The mediator-promoter repaired microbial damage by promoting intracellular chromium efflux. Moreover, the mediator-promoter reduced the accumulated reactive oxygen species by stimulating the secretion of antioxidant enzymes, reaching equilibrium in the oxidative-antioxidant system. To improve electron transmission, the mediator-promoter restored S2O32- oxidation to provide adequate electron donors and increased electron transfer rate by increasing cytochrome c levels. Mediator-promoter boosted the abundance of Thiobacillus (sulfur-oxidizing bacterium) and Simplicispira (denitrifying bacterium), which were positively correlated, facilitating the rapid denitrification recovery and the long-term stable operation of recovered systems.

Engineering time-dependent MOF-based nickel boride 2D nanoarchitectures as a positive electrode for energy storage applications

It is of great importance to design rationally combined metal-organic frameworks (MOFs) with multifunctional nano geometries to develop advanced energy storage devices. We devised a simple room-temperature boronization system to produce ultrathin Ni-ZIF/Ni-B nanosheets with plenty of crystalline-amorphous phase barriers. The Ni-ZIF/Ni-B-24 h nanoflakes electrodes exhibited a specific capacitance of 104.2F g−1 with the cyclic stability of 94.5 % using the flaky architecture and inherent properties of the Ni-ZIF/Ni-B-24 h nanoflakes. Furthermore, an asymmetric supercapacitor made of Ni-ZIF/Ni-B-24 h and activated carbon had a high specific capacitance of 370.7F g−1 at 1 A/g, and the energy density of 131.8 W h kg−1 at a power density of 800 W kg−1. Intriguingly, Ni-ZIF/Ni-B-24 h nanoflakes have consistently delivered higher specific capacities because of the adequate electrochemical active sites and an increase in electron transfer rate during redox reactions.

Enhancing perovskite solar cells: Tailoring the properties of Ti-doped MAPbBr3 for reduced recombination and improved efficiency

By using the sol-gel method, (0 %, 4 % and 6 %) Ti-doped MAPbBr3 films were deposited on FTO-glass substrates. XRD confirmed cubic structure of all films and the 4 % Ti-doped film has a large grain size of 80 nm. UV–Vis spectroscopy analysis confirmed that the 4 % Ti-doped film has low band gap energy of 2.36 eV, and a high refractive index of 2.62. The tuning of the conduction and valence band edges speeds up the movement of charges between the layers. The solar cells of these films have been fabricated with the geometry of glass/TiO2/Ti-MAPbBr3/spiro-OMeTAD/Au. The 4 % Ti-MAPbBr3 based cell showed high current density (9.15 mA/cm2), open circuit voltage (1.03 V), fill factor (0.7407), and efficiency (6.9804 %). EIS showed that the 4 % Ti-MAPbBr3 cell has an increased electron transfer rate and lowers the possibility of recombination at the TiO2/perovskite interface.

A Theoretical Molecular Design of Acridine/Anthracene‐Polyoxometalate Hybrid Materials for Enhanced Dye‐Sensitized Solar Cells Performance

AbstractFour novel organoimido‐substituted hexamolybdate dyes featuring acridine/anthracene donors for dye‐sensitized solar cells (DSSCs) have been designed and studied using a combination of density functional theory (DFT) and time‐dependent density functional theory (TDDFT) calculations. The energy levels of frontier molecular orbitals, absorption spectra with electronic transition characters, and photovoltaic parameters of dyes 1–4 were systematically evaluated. The results confirm the suitability of all the studied dyes for n‐type DSSCs. The investigated dyes could be introduced as an active co‐absorbent as well as main dye. All dyes showed remarkable reorganization energy for electron transport (λe) and hence increased electron transfer rate. Due to the strong absorption in the visible region, as well as high light harvesting efficiency (LHE), dye regeneration efficiency (DRE), and electron injection efficiency (Φinj), dyes 2 and 3 are the most promising candidates for high performance DSSC materials.

One-pot solvothermal synthesis of Bi/Bi2S3/Bi2WO6 S-scheme heterojunction with enhanced photoactivity towards antibiotic oxytetracycline degradation under visible light

A novel noble-metal-free ternary Bi/Bi2S3/Bi2WO6 S-scheme heterojunction and Schottky junction was successfully synthesized by one-pot solvothermal method. UV–Vis spectroscopy showed improved light absorption in the ternary composite structure. Electrochemical impedance spectroscopy and photoluminescence spectroscopy confirmed the reduced interfacial resistivity and photogenerated charge recombination rate of the composites. Using oxytetracycline (OTC) as model pollutant, Bi/Bi2S3/Bi2WO6 presented high photocatalytic activity towards OTC degradation, where the removal rate of Bi/Bi2S3/Bi2WO6 was 1.3 and 4.1 times higher than that of Bi2WO6 and Bi2S3 under visible light irradiation in 15 min, respectively. The excellent visible photocatalysis activity was attributed to the SPR effect of metal Bi and the direct S-scheme heterojunction of Bi2S3 and Bi2WO6 with the matched energy band structure, which led to the increased electron transfer rate and high separation efficiency of the photogenerated election-hole pairs. After seven cycles, the degradation efficiency for 30 ppm OTC with Bi/Bi2S3/Bi2WO6 only decreased 20.4%. In the degradation solution, the composite photocatalyst leached only 16 ng/L Bi and 26 ng/L W of metal with high photocatalytic stability. Moreover, free radical quenching experiment and electron spin-resonance spectroscopy experiment revealed that ·O2−, 1O2, h+ and ·OH played crucial roles in the photocatalytic degradation of OTC. Based on the analysis of high performance liquid chromatography-mass spectrometry for the intermediates in the degradation process, the degradation pathway was provided. Finally, combined with ecotoxicological effect analysis, the decreased toxicity of OTC after degradation towards rice seedlings was confirmed.

The Effects of Pt-Doped TiO2 Nanoparticles and Thickness of Semiconducting Layers at Photoanode in the Improved Performance of Dye-Sensitized Solar Cells.

This work synthesized Pt-doped dye-sensitized solar cells (DSSC) with different molar ratios and thicknesses. The materials were revealed fully through X-ray diffraction (XRD), energy-dispersive spectroscopy (EDS), and transmission electron microscopy (TEM). The photovoltaic properties of the sample were studied by UV-visible spectroscopy, electrochemical impedance spectroscopy (EIS), and IPEC (incident photon-to-current conversion efficiency) techniques. EIS analysis established the decrease in series resistance at the electrolyte interface. It could be one of the reasons for the increase in electron transfer rate and decrease in the recombination process at the interface. Statistical data obtained from optical and electrical investigations revealed that the electrical power-output efficiency of DSSC was 14.25%. It was found that a high ratio of Pt doping and thinner thickness can promote cell performance, owing to the reduction of series resistance, lower bandgap, and high dye adsorption. Doping TiO2 with Pt reduced its energy bandgap and introduces intermediate energy levels inside TiO2 to facilitate the transition of electrons at low excitation energies. The absorbance of the samples 0.15 M Pt and 0.25 M Pt showed improvement in the wavelength ranging from 200 to 800 nm by Pt doping.

Development of an electrochemical sensor based on Ce3+ and CuO for the determination of amaranth in soft drinks

A novel Ce3+-doped CuO nanocomposite was synthesized in the present study. The proposed modified carbon paste electrode (Ce3+-doped CuO/CPE) was applied to detect amaranth. Cyclic voltammetry and differential pulse voltammetry were employed to evaluate the electrochemical responses of modified electrode. The oxidation signal of Ce3+-doped CuO/CPE in the presence of amaranth was enhanced which could be related to the synergistic effect of cerium and CuO that improved the electrochemical behavior of electrode for oxidation of amaranth. In this study, the surface areas of bare, CuO/CPE and Ce3+-doped CuO/CPE were calculated 0.043, 0.131 and 0.147 cm2, respectively. The presence of Ce3+-doped CuO at the electrode surface, effectively increased electron transfer rate and surface area which improved the sensitivity of electrode for amaranth determination. Using the scan rate, a diffusion-controlled electrochemical process for the amaranth oxidation on Ce3+-doped CuO/CPE was confirmed. The diffusion coefficient of 1.37×10−5 cm2 s−1 for amaranth was calculated based on the chronoamperometry analysis. The response was linearly for amaranth in the range between 0.05 and 240.0 μM and the limit of detection and limit of quantification were calculated to be 10.2 and 30.9 nM, respectively. Based on the results, the present electrode showed suitable stability, reproducibility and repeatability for amaranth detection. In addition, the proposed electrode was employed to detect amaranth in real specimens, the results of which showed successful outputs.

Ce2(MoO4)3 synthesized with oleylamine and oleic acid as additives for photocatalysis: effect of preparation method.

Ce2(MoO4)3 was prepared using dielectric barrier discharge (DBD) plasma method, co-precipitation method and hydrothermal method, respectively, with water/ethanol (W/O) as solvent, oleylamine (OAm) and oleic acid (OAc) as additives. Preparation method showed significant influence on the morphological and structural properties, as well as photocatalytic performance. Ce2(MoO4)3 synthesized with DBD plasma (MO-P) was mainly flowerlike nanosheets, which were beneficial to promoting electron transfer and providing more space for catalytic activity. Also, MO-P samples exhibited more oxygen vacancies, which were conducive to the photocatalytic performance. What's more, MO-P showed lower PL intensity and narrow energy gap, which implied a slow photoelectron-hole pair recombination rate and an increased electron transfer rate. The degradation rate of methyl orange (50mg/L) could achieve 98% within 12min with 0.5g/L MO-P. Hydroxyl radicals (·OH) and superoxide radicals (·O2-) played a major effect. Plasma synthesis method exhibited potential application prospect in photocatalysts preparation.

Development of [I(ads)|Au(pc)] electrode to attain electrocatalytic oxidation of paracetamol: An efficient platform for quantitative analysis

Electrochemical oxidation of paracetamol (PCT) has exclusively been investigated using polycrystalline gold electrode modified with iodine adlayer [I(ads)|Au(pc)] in alkaline medium. Irreversible adsorption of PCT makes Au(pc) surface unfeasible for studying PCT oxidation reaction. This limitation of Au(pc) surface could be eliminated simply by iodide (I-) adsorption. It was noticed that the spontaneous I- adsorption blocks PCT adsorption sites on Au(pc) surface, which additionally improves PCT oxidation reaction by increasing electron transfer rate. Iodine adlayer (I-adlayer) formulated electrode facilitated PCT electro-oxidation via an alternative diffusion-controlled pathway with an anodic electron transfer coefficient (β) of 0.47 and heterogeneous rate constant (ko) of 0.0911 cm s−1 where an electron transfer step determines the reaction rate. The sensing experiments revealed that the [I(ads)|Au(pc)] electrode attained linear dynamic range from 4.5 to 1600 μM of PCT. The obtained sensitivity and limit of detection (LOD) of the [I(ads)|Au(pc)] electrode surface was determined to be 8.37( ± 1.6)× 10−4 mA cm−2 μM−1 and 0.65 ± 0.02 μM, respectively. The formulated [I(ads)|Au(pc)] catalyst was applied to quantify the relative PCT percentage in commercial tablets using batch injection analysis supported by chronoamperometry. Obtained relative percentage closely matched with the corresponding analysis performed with Raman spectroscopy. Therefore, developed I-adlayer coated Au(pc) electrode is analytically robust and validated for routine analysis of PCT concentration in relevant pharmaceutical applications.

Improved Electroactivity of Redox Probes onto Electropolymerized Azidomethyl-PEDOT: Enabling Click Chemistry for Advanced (Bio)Sensors

We report on improved electroactivity of redox probes onto chloromethyl- and azidomethyl-substituted poly(3,4-ethylenedioxythiophene) in terms of up to a 2000-fold increased electron transfer rate....

Novel determination of Cd and Zn in soil extract by sequential application of bismuth and gallium thin films at a modified screen-printed carbon electrode

This study describes a novel electrochemical technique for the detection of bioavailable cadmium(II) (Cd) and zinc(II) (Zn), in real soil samples. This was made possible by the sequential deposition of bismuth and gallium thin films on modified screen-printed carbon electrodes (SPEs). A range of graphitic modifications were evaluated, and a reduced graphene oxide/graphitic carbon nitride (RGO/g-C3N4) modification proved most suitable. Electrochemical characterisation demonstrated superior stability, attributed to the functional groups of GO, and an increased electron transfer rate, attributed to the intercalated g-C3N4.For voltammetric analysis, cadmium was determined in acetate buffer (pH 4.6) using a bismuth thin film (BiTF). Zn was then determined in the same cell, after adjustment of the pH to 5.1, using a gallium thin film (GaTF). The rationale for two separate thin films is described. Optimisations, such as concentration of bismuth(III), gallium(III), potassium ferrocyanide, pH and deposition potentials, were conducted in the matrix of real samples. The LODs and LOQs were determined in the extracted soil matrix as 0.01 and 0.03 mg kg−1, respectively, for bioavailable Cd and 0.01 and 0.04 mg kg−1, respectively, for bioavailable Zn. Good agreement was observed for Cd and Zn levels in numerous soil samples when compared to the established technique of ICP-OES. This approach opens up the possibility for rapid on-site portable testing of Cd and Zn in real soil samples to determine the probability of Cd uptake by crops.

Carbon/Sulfur Aerogel with Adequate Mesoporous Channels as Robust Polysulfide Confinement Matrix for Highly Stable Lithium-Sulfur Battery.

The ability to restrict the shuttle of lithium polysulfide (LiPSn) and improve the utilization efficiency of sulfur represents an important endeavor toward practical application of lithium-sulfur (Li-S) batteries. Herein, we report the crafting of a robust 3D graphene-wrapped, nitrogen-doped, highly mesoporous carbon/sulfur (G-NHMC/S) hierarchical aerogel as an effective polysulfide confinement matrix for a highly stable Li-S battery. Rich polar sites of NHMC firmly anchor LiPSn on the matrix surface. Porous NHMC provides ample space for accommodating sulfur and cushioning its volume expansion. Moreover, graphene wrapped on NHMC/S not only physically hinders the LiPSn shuttle but also interconnects the isolated NHMC/S, thus increasing electron transfer rate. Taken together, triple confinement of G-NHMC/S aerogel synergistically retains the soluble LiPSn and displays a specific capacity of 1322 mAh g-1 and 1000-cycle life. As such, rationally designed 3D carbon/sulfur aerogel affords a unique platform to impart high energy density and stable electrodes for energy storage devices.

Purposely Designed Hierarchical Porous Electrodes for High Rate Microbial Electrosynthesis of Acetate from Carbon Dioxide.

Carbon-based products are crucial to our society, but their production from fossil-based carbon is unsustainable. Production pathways based on the reuse of CO2 will achieve ultimate sustainability. Furthermore, the costs of renewable electricity production are decreasing at such a high rate, that electricity is expected to be the main energy carrier from 2040 onward. Electricity-driven novel processes that convert CO2 into chemicals need to be further developed. Microbial electrosynthesis is a biocathode-driven process in which electroactive microorganisms derive electrons from solid-state electrodes to catalyze the reduction of CO2 or organics and generate valuable extracellular multicarbon reduced products. Microorganisms can be tuned to high-rate and selective product formation. Optimization and upscaling of microbial electrosynthesis to practical, real life applications is dependent upon performance improvement while maintaining low cost. Extensive biofilm development, enhanced electron transfer rate from solid-state electrodes to microorganisms and increased chemical production rate require optimized microbial consortia, efficient reactor designs, and improved cathode materials. This Account is about the development of different electrode materials purposely designed for improved microbial electrosynthesis: NanoWeb-RVC and EPD-3D. Both types of electrodes are biocompatible, highly conductive three-dimensional hierarchical porous structures. Both chemical vapor deposition (CVD) and electrophoretic deposition were used to grow homogeneous and uniform carbon nanotube layers on the honeycomb structure of reticulated vitreous carbon. The high surface area to volume ratio of these electrodes maximizes the available surface area for biofilm development, i.e., enabling an increased catalyst loading. Simultaneously, the nanostructure makes it possible for a continuous electroactive biofilm to be formed, with increased electron transfer rate and high Coulombic efficiencies. Fully autotrophic biofilms from mixed cultures developed on both types of electrodes rely on CO2 as the sole carbon source and the solid-state electrode as the unique energy supply. We present first the synthesis and characteristics of the bare electrodes. We then report the outstanding performance indicators of these novel biocathodes: current densities up to -200 A m-2 and acetate production rates up to 1330 g m-2 day-1, with electron and CO2 recoveries into acetate being very close to 100% for mature biofilms. The performance indicators are still among the highest reported by either purposely designed or commercially available biocathodes. Finally, we made use of the titration and off-gas analysis sensor (TOGA) to elucidate the electron transfer mechanism in these efficient biocathodes. Planktonic cells in the catholyte were found irrelevant for acetate production. We identified the electron transfer to be mediated by biologically induced H2. H2 is not detected in the headspace of the reactors, unless CO2 feeding is interrupted or the cathodes sterilized. Thus, the biofilm is extremely efficient in consuming the generated H2. Finally, we successfully demonstrated the use of a synthetic biogas mixture as a CO2 source. We thus proved the potential of microbial electrosynthesis for the simultaneous upgrading of biogas, while fixating CO2 via the production of acetate.

Three-Dimensional Sulfite Oxidase Bioanodes Based on Graphene Functionalized Carbon Paper for Sulfite/O2 Biofuel Cells

We have developed a three-dimensional (3D) graphene electrode suitable for the immobilization of human sulfite oxidase (hSO), which catalyzes the electrochemical oxidation of sulfite via direct electron transfer (DET). The electrode is fabricated by drop-casting graphene-polyethylenimine (G-P) composites on carbon papers (CPs) precoated with graphene oxide (GO). The negatively charged hSO can be adsorbed electrostatically on the positively charged matrix (G-P) on CP electrodes coated with GO (CPG), with a proper orientation for accelerated DET. Notably, further electrochemical reduction of G-P on CPG electrodes leads to a 9-fold increase of the saturation catalytic current density (jm) for sulfite oxidation reaching 24.4 ± 0.3 μA cm–2, the highest value among reported DET-based hSO bioelectrodes. The increased electron transfer rate plays a dominating role in the enhancement of direct enzymatic current because of the improved electric contact of hSO with the electrode. The optimized hSO bioelectrode shows...

Vibrational coherence in ultrafast electron transfer reaction observed by broadband transient absorption spectroscopy

Photoinduced electron transfer (ET) is one of the most important processes in light energy conversion systems. Marcus theory is one of the most famous frameworks on ET reaction in condensed phase. In this theory, reorganization of surrounding media is regarded as a main reaction coordinate. However, ultrafast ET beyond Marcus’ framework has been reported in various systems. To elucidate the role of molecular vibration in ultrafast ET, we have investigated the ET dynamics between a naphthacene dye and aniline derivatives by means of broadband transient absorption spectroscopy. Coherent wavepacket motions of naphthacene dye with frequencies of 300-1600 cm-1 were observed in time domain. The vibrational coherence of 310 cm-1 mode was reduced with increasing electron transfer rate, suggesting this vibration is coupled to electron transfer reaction.

Electro-Fenton degradation of ciprofloxacin with highly ordered mesoporous MnCo2O4-CF cathode: Enhanced redox capacity and accelerated electron transfer

The emergence of antibiotics in the environment, especially in drinking water, poses potential harm to human health. It’s urgent to develop effective methods to remove antibiotics in drinking water. In this work, a series of mesoporous MnxCo3−xO4 nanoparticles with high surface area were successfully synthesized and firstly used as effective stable electro-Fenton catalysts to degrade ciprofloxacin (CIP). The removal of CIP achieved to 100% within 5 h. Experimental and density functional theory (DFT) studies verified the existence of redox pairs of Mn2+/Mn3+ and Co2+/Co3+. Scanning electrochemical microscopy (SECM) results suggested that the redox reaction capacity of MnCo2O4 was enhanced and the electron transfer rate on the surface of this bimetallic oxide was 2.67 and 1.6 times the number of MnO2 and Co3O4, respectively. The effective degradation of CIP was mainly associated with the increased electron transfer rate and advanced redox reactivity owing to the synergistic effect of manganese and cobalt entrapped in the matrix of mesoporous structure which provided more accessible active sites. The degradation intermediates and possible process mechanism were investigated in detail. The reusability of MnCo2O4-CF cathode was evaluated five cycles with minimal ion leaching which the concentration of Mn and Co in the system was lower than 2.5 and 3.4 ppm, respectively. This work provides further understanding for removal process of organic pollutants by investigation of redox couple and electron transfer rate of the promising MnCo2O4-CF cathode.

A new insight into the strategy for methane production affected by conductive carbon cloth in wetland soil: Beneficial to acetoclastic methanogenesis instead of CO2 reduction

Conductive materials/minerals can promote direct interspecies electron transfer (DIET) between syntrophic bacteria and methanogens in defined co-culture systems and artificial anaerobic digesters; however, little is known about the stimulation strategy of carbon material on methane production in natural environments. Herein, the effect of carbon cloth, as a representative of conductive carbon materials, on methane production with incubated wetland soil was investigated. Carbon cloth significantly promoted methanogenesis. With the application of electrochemical technology, calculation of the apparent electron transfer rate constant showed that carbon cloth significantly increased electron transfer rate (ETR) compared with the control experiment in presence of cotton cloth, from 0.0017 ± 0.0003 to 0.0056 ± 0.0015 s−1. Results obtained from both stable carbon isotope measurements and application of specific inhibitor (CH3F) for acetoclastic methanogenesis indicated that carbon cloth obviously promoted acetoclastic methanogenesis instead of CO2 reduction. High-throughput sequencing showed that methane production may stem from the involvement of Methanosarcina for both treatments. Our findings suggested that conductive carbon material can promote acetoclastic methanogenesis instead of CO2 reduction in a natural environment.

Theoretical Modeling, Facile Fabrication, and Experimental Study of Optimally Bound Bilirubin Oxidase on Palladium Nanoparticles for Enhanced Oxygen Reduction Reaction

This paper presents an optimally bound bilirubin oxidase (BOD) (Myrothecium verrucaria) on palladium nanoparticles (Pd NPs) for enhanced oxygen reduction reaction (ORR). Theoretical modeling of BOD on Pd demonstrated that Pd has strong preferential binding to BOD via T1 copper (Cu) site because of its high adsorption energy. This preferential binding was accompanied by a reduction in distance between the Cu active sites and Pd which would result in an increase in electron transfer rate (kcat) and an enhancement in catalytic activity of BOD. Inspired by the computational results, a biocathode comprising carbon nanotube (CNT), Pd NPs, and BOD (CNT-Pd-BOD) was facilely fabricated using an electroless deposition method. The CNT-Pd-BOD biocathode exhibited higher catalytic activity (1.52 times) and kcat (1.71 times) when compared with CNT-BOD only biocathode. These results demonstrate Pd NPs as a suitable substrate for preferential binding with BOD to increase catalytic activity.