Anion-tuning of cobalt-based chalcogenides for efficient oxygen evolution in weakly alkaline seawater

Regulating the electronic structure is of great importance for improving the performance, stability, and selectivity of seawater splitting catalysts. Herein, cobalt-based oxide and chalcogenide (Co3X4, X = O, S, and Se) are synthesized to investigate the effect of anions on the electronic structure, catalytic perfor-mance and selectivity of the seawater oxidation catalysts. The theoretical calculations predict the possi-ble active sites of oxygen evolution reaction and hypochlorite evolution reaction. Then the experimental characterization and calculation results demonstrate that S and Se substitution could regulate the elec-tronic structure and d-band center of Co site, enhance the metallicity of catalysts. Moreover, the energy barrier of Cl* conversion to ClO- could be modulated for preventing the formation of ClO- by anions reg-ulating. Consequently, Co3S4 could stably operate at a current density of 100 mA cm -2 in 0.1 M KOH + 0.6 M NaCl for 100 h and in neutral seawater for 20 h.(c) 2022 Elsevier Ltd. All rights reserved.

Automated summary

This study synthesized cobalt-based oxide and chalcogenide (Co3X4, X = O, S, and Se) to investigate the effects of anions on the electronic structure, catalytic performance, and selectivity of seawater oxidation catalysts. Experimental and theoretical results showed that the substitution of S and Se could regulate the electronic structure and d-band center of Co site, enhancing the metallicity of the catalysts. Additionally, anions were able to modulate the energy barrier for preventing the formation of ClO-. Therefore, Co3S4 exhibited stable performance in 0.1 M KOH + 0.6 M NaCl for 100 hours and in neutral seawater for 20 hours.