Constructing of non-precious metal-based NiCo bimetallic aerogel by thermal reduction of carbon species under elevated temperatures for efficient oxygen evolution reaction

Hydrogen and oxygen, as renewable secondary energy sources, are assuming an increasingly significant role in mitigating fossil energy consumption and diminishing environmental pollution. The development of oxygen evolution reaction (OER) electrocatalysts in the anode with low-cost, highly efficient, and stable properties remains a big challenge, where the non-precious metal aerogel-based electrocatalyst with exposed active sites and diffusion channels has attracted much attention. However, the metal aerogel is conventionally prepared using chemical reduction agents, such as NaBH₄, Glyoxylic acid monohydrate, and lithium aluminum hydride, etc., yet the reaction is dramatic and unsafety, therefore limiting its industrialization. Herein, a novel NiCo aerogel catalyst is obtained from carbon reduction derived from phthalic acid under high temperature via the oxide-based aerogel, which is formed under the crosslink reaction derived by propylene epoxide, combined with the polyacrylic acid template. The NiCo aerogel catalyst shows a typical three-dimensional porous structure, with a large Brunauer–Emmett–Teller (BET) specific surface area of 227.84 m² g⁻¹. The alloy aerogel displays excellent OER activity with an overpotential of 330 mV at a current density of 10 mA cm⁻², a low Tafel slope of 69.50 mV dec⁻¹, and a long-term stability of at least 72,000 s, exceeding the commercial RuO₂ catalyst. The NiCo bimetallic aerogel can be easily transformed into the NiCo-layered double hydroxide (LDH) structure. The density functional theory (DFT) calculations reveal that the formation of the LDH structure can increase the adsorption strength of *OOH as compared with the pristine NiCo alloy, and thus enhances the OER performance. Moreover, the outstanding OER catalytic properties can be ascribed to the synergetic effect of the hierarchical porous structure, accelerating the diffusion of intermediate and exposed active sites, high electrical conductivity derived from the porous carbon support, along with the electron structure modulation within the NiCo LDH structure.