Interfacial electronic engineering of co-doped Ni(OH)2 nanoarrays for efficient electrooxidation of xylose to formate

Abstract

The electrochemical oxidation of biomass-derived xylose (XOR) to formate offers a sustainable route for chemical production and renewable energy integration. However, conventional Ni-based catalysts suffer from a high overpotential for generating the active Ni³⁺ species and competing side reactions, which limit their achievable current density and selectivity. Herein, we design Co-doped Ni(OH)₂ nanoarrays on carbon felt to overcome these limitations. The catalyst exhibits an exceptionally low potential of 1.34 V vs. RHE at 100 mA cm⁻² for XOR, which is 242 mV lower than that for the oxygen evolution reaction, while delivering a formate faradaic efficiency >92% and maintaining stable performance over 132 hours at 250 mA cm⁻². Mechanistic studies reveal that Co doping induces electron transfer from Ni to Co via bridging oxygen atoms, forming Ni–O–Co interfacial units that serve as efficient electron channels to accelerate charge transfer and reduce the energy barrier for Ni³⁺ formation. Coupled with a superhydrophilic and superaerophobic nanoarray architecture that ensures superior mass transport, the catalyst delivers stable, high-rate performance. This work elucidates the role of interfacial electronic engineering and nanostructure design in modulating reaction energetics, providing an effective strategy for high-performance biomass electrooxidation.