One-step, room temperature generation of porous and amorphous cobalt hydroxysulfides from layered double hydroxides for superior oxygen evolution reactions

Abstract

Porous and amorphous materials are extensively studied in various applications on account of their high surface area and catalytic active sites. In this work, we for the first time came up with a convenient and effective method for selectively etching amphoteric Al and the sulfurization of CoAl-LDH in one step (at room temperature) to synthesize a kind of porous and amorphous CoS_x(OH)_y nanosheet (PA-CoS_x(OH)_y). Compared with CoAl-LDH, and only etched and only sulfurized CoAl-LDH (abbreviated to OE-CoAl-LDH and OS-CoAl-LDH), PA-CoS_x(OH)_y exhibited a much better electrochemical OER activity. Moreover, the OER performance of PA-CoS_x(OH)_y can be further enhanced by being directly loaded on nickel foam (NF). When the current density reached 10 mA cm⁻², the overpotential of PA-CoS_x(OH)_y/NF was only 261 mV. Adjustment of the physical structure and electronic state of the catalyst can significantly improve the electrocatalytic performance. The porous and amorphous properties of PA-CoS_x(OH)_y exposed a large amount of active sites and enhanced the electrocatalytic performance. The synergy effect between S and OH and the oxygen vacancies would regulate the electronic structure of the catalyst. This causes it to have outstanding OER electrocatalytic activity and stability in alkaline medium.