In-Situ Transformation and Synergistic Electrocatalysis of Asymmetric Threefold Hollow Sites in Rosebud-Like Ternary Metal Diselenide

Abstract

Electrochemical dynamic reconstruction substantially optimizes the catalytic properties of transition-metal-based precatalysts for the multi-electron oxygen evolution reaction (OER) by altering the surface structure, exposing more active sites, improving electron/ion transport, and enhancing stability. This research provides a comprehensive understanding of the in-situ transformation manner of a rosebud-like ternary metal diselenide precatalyst (Ni0.8Fe0.2Co0.1Se2) and the synergistic electrocatalytic mechanism of catalytic active centers through in-situ and ex-situ characterization along with DFT calculations. Benefiting from the unique morphology and abundant nanoscale planar defects within the conductive Ni0.8Fe0.2Co0.1Se2 core and the in-situ formed catalytically active (Fe, Co)-doped γ-NiOOH shell, the reconstructed catalyst achieves rapid electron/ion transport and copious active site exposure. Accordingly, the Ni0.8Fe0.2Co0.1Se2 catalyst only requires overpotentials of 101 mV and 233 mV to achieve current densities of 10 mA cm−2 and 100 mA cm−2, respectively. The overall water-splitting cell using Ni0.8Fe0.2Co0.1Se2 anode delivers current densities of 10 and 100 mA cm−2 at low cell voltages of 1.41 and 1.56 V, respectively. Furthermore, the cell demonstrates exceptional durability of 400 h at an industrial-level current density. This work sheds light on the development of efficient transition-metal-based precatalysts for OER.

Keywords: surface reconstruction, synergistic effect, active sites, Transition metal selenides, water electrolysis