A fast and in-depth self-reconstruction of anion ligands optimized CoFe-based pre-catalysts for water oxidation

The design of efficient and robust non-precious metal electrocatalysts towards oxygen evolution reaction (OER) is of great value for developing green energy technologies. The in-situ formed high-valence (oxy)hydroxides species during the reconstruction process of pre-catalysts are recognized as the real contributing sites for OER. However, pre-catalysts generally undergo a slow and inadequate self-reconstruction. Herein, we reported a PO43− optimized CoFe-based OER catalysts with amorphous structure, which enables a fast and deep reconstruction during the OER process. The amorphous structure induced by ligands PO43− is prone to evolution and further form active species for OER. The electron interaction between metal sites can be modulated by electron-rich PO43−, which promotes generation of high active CoOOH. Simultaneously, the etching of PO43− from the pre-catalysts during the catalytic process is in favor of accelerating the self-reconstruction. As a result, as-prepared pre-catalyst can generate high active CoOOH at a low potential of 1.4 V and achieve an in-depth reconstructed nanosheet structure with abundant OER active sites. Our work provides a promising design of pre-catalysts for realizing efficient catalysis of water oxidation. PO43− optimized pre-catalyst is able to achieve a rapid and deep reconstruction, which generates active CoOOH species at a low potential of 1.4 V and deeply transforms into nanosheets with enriched active species. The evolved catalysts exhibit the greatly improved OER catalytic activity with decent durability. [Display omitted] •Operando Raman characterization shows that the a-CoFeO-PO4 can generate OER active species at a low potential of 1.4 V.•The PO43− can promote the formation of active species during catalytic process•The a-CoFeO-PO4 transformed into deep reconstructed nanosheet structure, which presents decent catalytic performance.