Sulfur filling activates vacancy-induced C–C bond cleavage in polyol electrooxidation
Jianqiao Shi, Wei Chen, Yandong Wu, Yanwei Zhu, Chao Xie, Yimin Jiang, Yucheng Huang, Chung‐Li Dong, Yuqin Zou
Abstract
ABSTRACT Using the electrochemical polyol oxidation reaction (POR) to produce formic acid over nickel-based oxides/hydroxides (NiOxHy) is an attractive strategy for the electrochemical upgrading of biomass-derived polyols. The key step in the POR, i.e. the cleavage of the C–C bond, depends on an oxygen-vacancy-induced mechanism. However, a high-energy oxygen vacancy is usually ineffective for Schottky-type oxygen-vacancy-rich β-Ni(OH)2 (VSO-β-Ni(OH)2). As a result, both β-Ni(OH)2 and VSO-β-Ni(OH)2 cannot continuously catalyze oxygen-vacancy-induced C–C bond cleavage during PORs. Here, we report a strategy of oxygen-vacancy-filling with sulfur to synthesize a β-Ni(OH)2 (S-VO-β-Ni(OH)2) catalyst, whose oxygen vacancies are protected by filling with sulfur atoms. During PORs over S-VO-β-Ni(OH)2, the pre-electrooxidation-induced loss of sulfur and structural self-reconstruction cause the in-situ generation of stable Frenkel-type oxygen vacancies for activating vacancy-induced C–C bond cleavage, thus leading to excellent POR performances. This work provides an intelligent approach for guaranteeing the sustaining action of the oxygen-vacancy-induced catalytic mechanism in electrooxidation reactions.