Hollow double-shell Co3O4@CoNiSx p-n heterojunction for enhanced visible light-assisted methanol electrocatalytic oxidation

Abstract

Accelerating the separation of photogenerated carriers and improving the diffusion efficiency of reactants is an effective way to improve the photoelectric catalytic activity of catalysts. In this report, a dual-scale optimization strategy combining atomic-scale built-in electric field construction with molecular-level hollow structure construction was proposed to enhance the visible photo-assisted methanol electrocatalytic oxidation activity of cobalt nickel based non-noble metal catalysts. Using ZIF-67 as self-sacrifice template, through a three-steps strategy containing cation exchange, L-cysteine controlled etching, and high-temperature calcination, double-shell Co₃O₄@CoNiS_x nanocage was synthesized. The p-n junction formed between the inner shell (p type semiconductor Co₃O₄) and outer shell (n type semiconductor CoNiS_x) can effectively accelerate the separation of photogenerated carriers, and the hollow structure can improve the light adsorption and accelerate the diffusion of the reactants. The photoresponse current density of Co₃O₄@CoNiS_x (1.12 A g^-1) for visible light-assisted methanol electrocatalytic oxidation was two times and three times higher than that of single shell Co₃O₄@CoNiO_x and single component Co₃O_4. The dual-scale optimization strategy proposed in this report will be a general pathway for enhancing the photo-electrocatalytic activity of non-noble metal based photo-electro catalyst.