Multifunctional carbon-armored Ni electrocatalyst for hydrogen evolution under high current density in alkaline electrolyte solution

This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this record ; Data Availability: Data will be made available on request. ; Hydrogen evolution reaction (HER) electrocatalysts capable of long-term operation under high current densities are key to the industrialization of water-splitting technology. Although numerous efforts have been devoted to expose active sites sufficiently while increasing the intrinsic catalytic activity, effects of non-kinetic factors on catalytic efficiency have not yet been comprehensively investigated. Herein, multifunctional carbon-armored nickel nanoparticles (NC@NiNPs) were fabricated using an in-situ polymer encapsulation method for use as a HER electocatalyst. NC@NiNPs exhibited low overpotential (74 mV at 10 mA cm-2), low Tafel slope (85.49 mV dec-1) and excellent stability (over 260 h at 1400 mA cm-2). Surprisingly, although the intrinsic activity of NC@NiNPs was lower than that of commercial 20 % Pt/C, NC@NiNPs provided markedly greater current density than 20 % Pt/C as the operating voltage was increased. This result implied that non-kinetic factors influenced the HER process, prompting this investigation to identify these unknown factors. ; Chongqing Key Laboratory of Green Aviation energy and power, Chongqing, China ; National Natural Science Foundation of China ; Venture & Innovation Support Program for Chongqing Overseas Returnees ; Chongqing Engineering Research Center for Micro-Nano Biomedical Materials and Devices ; Chongqing Key Laboratory for Advanced Materials and Technologies, Chongqing Doctoral Research and Innovation Project