Anode-cathode interchangeable strategy for in situ reviving electrocatalysts' critical active sites for highly stable methanol upgrading and hydrogen evolution reactions.

Surface re-construction was a common phenomenon for non-oxide compound electrocatalysts in anodic oxidation reaction in alkaline electrolyte but surface deactivation arising from excessive oxidation/hydroxylation was critical hindrance to the long-term stability. Herein, a unique anode-cathode interchangeable electrocatalysis strategy is proposed for methanol upgrading reaction (MUR) and hydrogen co-generation in membrane-free electrolyzer. A periodical electrolysis is taken place for the Ni 3 S 2 /CNTs electrode at positive/negative currents over time. Compared with the traditional chronopotentiometry mode, the MUR-HER coupled reactions by periodically switching anode/cathode per hour present an excellent long-term stability at high current densities of ± 100 mA cm−2, in which the Faradaic efficiencies for both H 2 and value-added formate are greater than 95%. Substantial experimental results and deep theoretical DFT studies signify that the successful application of this strategy is mainly due to the reversible modulation of oxidation/hydroxylation status on Ni 3 S 2 surface, which effectively prevent the surface active structures of electrocatalysts from over-oxidation. [Display omitted] • A periodical electrolysis is taken place with Ni 3 S 2 /CNTs electrode at positive or negative current over time. • Long-term stable methanol upgrading and hydrogen co-generation are achieved in a membrane-free electrolyzer. • Substantial XPS, XAFS and DFT studies indicate that the surface critical active sites can be in situ revived. • Such unique anode-cathode interchangeable strategy effectively prevents catalyst surface from over-oxidation. • It successfully brings about the reversible modulation of oxidation/hydroxylation status on Ni 3 S 2 surface. [ABSTRACT FROM AUTHOR]