Chitosan‐Derived NiO‐Mn₂O₃/C Nanocomposites as Non‐Precious Catalysts for Enhanced Oxygen Reduction Reaction

Abstract

NiO‐Mn2O3/C nanocomposite was synthesized from chitosan, a renewable biopolymer, NiO and MnO2 and pyrolyzed at 500 °C under nitrogen. The morphology of material was characterized with various microscopic analyses. The graphitic carbon showed metal nanoparticles dispersed on the nanocomposite that could be clearly differentiated. X‐ray photoelectron spectroscopy indicated the Mn species reduced from +4 to +3 oxidation state, while Ni species remained as NiO, which was further supported by X‐ray diffraction. The electrochemical behavior of NiO‐Mn2O3/C toward oxygen reduction reaction (ORR) in alkaline medium was investigated via cyclic voltammetry (CV). CVs revealed a ORR peak at 0.67 V vs. RHE with significantly high current density. Hydrodynamic studies indicated that NiO‐Mn2O3/C catalyzed ORR via a four‐electron reduction pathway. A high rate constant in the order of magnitude of 106 mol−1s−1 was obtained for ORR. This low‐cost, environmentally friendly and stable ORR catalyst derived from chitosan and doped with metal oxides proved to be a promising electrocatalyst for ORR and could alternatively find its application in alkaline fuel cells (AFCs).

Earth abundant materials beyond transition metal dichalcogenides: A focus on electrocatalyzing hydrogen evolution reaction

“…Transition metal oxides (TMOs) have been widely used in fields of oxygen evolution reaction (OER) [259][260][261], oxygen reduction reaction (ORR) [262][263][264], and photochemical reduction reaction [265][266][267] owing to their environmentally benignity, stability and cost-effective characteristics. Unfortunately, most metal oxides fail to electrocatalyze hydrogen evolution reaction due to their low intrinsic electrical conductivity and inappropriate free energy of hydrogen adsorption [268][269][270][271][272][273].…”

Nickel-Based Hybrid Material for Electrochemical Oxygen Redox Reactions in an Alkaline Medium

“…The average n value (∼3.3) calculated from the RRDE analysis revealed that the Ni-BTB-BPE/C favors the four-electron pathway in 0.1 M KOH. The ORR onset potential and n value of several non-porous Ni-based catalysts are listed in Table S3. − For molecular catalysts such as metal macrocycles, MOFs, or MOCs or CP, four-, and two-electron TOF values of ORR specify a quantitative description for selectivity of the ORR catalytic pathway. Using the Ni-BTB-BPE loading (19.6 μg) on RRDE and its molecular weight and formulae (1066.02 g/mole, obtained from single crystal data) information, the Ni sites were calculated to be 44.28 × 10 15 (375 nM cm –2 ).…”

Microwave‐Assisted Rapid Preparation of Vermiculite‐Loaded Nano‐Nickel Oxide As a Highly Efficient Catalyst for Acetylene Carbonylation to Synthesize Acrylic Acid

“…By performing the peak fitting analysis, it is determined that Ni 2p3/2 exhibits two characteristic peaks . The peak at 854.7 eV is attributed to the Ni 2+ species on the surface of NiO, 856.4 eV is attributed to Ni 3+ species induced by the Ni−O octahedral N 2+ vacancy, and the satellite peak was observed at 862.2 eV . These results explain the presence of NiO in this catalyst; NiO is considered to be the active site for acetylene carbonylation, and its load is critical (Table ).…”