晶格Zn诱导Co₃O₄表面活性位重构及其酸性电催化产氧研究

Global industrialization has led to the increased consumption of fossil fuels such as coal, oil, and natural gas, which release large amounts of carbon dioxide and threaten human society. Thus, it is urgent to eliminate reliance on fossil fuels and develop clean energy. Hydrogen, especially green hydrogen from renewable-electricity-powered water electrolysis, is a promising and competitive candidate for next-generation clean energy carriers. Among various water electrolysis technologies, the proton exchange membrane water electrolyzer (PEMWE) has garnered global attention due to high current density (exceeding 1 A cm^–2), high hydrogen purity (over 99.99%), and rapid response (less than 5 s) for intermittent renewable electricity. However, the industrial application of PEMWE is significantly hindered by the absence of highly active and stable non-noble metal-based electrocatalysts at the anode for the acidic oxygen evolution reaction (OER). Among the various non-noble metal-based electrocatalysts developed for OER in past years, cobalt oxide (Co₃O₄) has exhibited distinguished performances in electrocatalytic water splitting under acidic conditions, along with its high resistance against acid corrosion and relatively abundant reserves. Previous in-situ spectral investigations revealed that the surface reconstruction process would happen to the as-obtained (Co₃O₄ electrocatalysts at anodic potentials, which created high-valence Co⁴⁺ acting as the actual active sites for the acidic OER. Given the electrocatalytic activity and stability of (Co₃O₄ depending on the high-valence Co⁴⁺ active sites, understanding and regulating the surface reconstruction process over the obtained (Co₃O₄ electrocatalysts is highly desired for the design of non-noble metal-based electrocatalysts with high activity and excellent stability for OER. Herein, Zn atoms were uniformly doped into the lattice of (Co₃O₄ (Zn-(Co₃O₄), as derived from metal organic framework (MOFs), with the atomic coordination structure of Co^2+/3+ sites optimized to be responsible for the controlled surface reconstruction of (Co₃O₄. With the acidic OER performance measured in 0.5 mol/L H₂SO₄ electrolyte in a three-electrode system, the obtained Zn-(Co₃O₄ electrode could achieve a low overpotential of 317 and 549 mV at the current density of 10 and 100 mA cm^–2, respectively, and a long-term stability exceeding 70 h at 10 mA cm^–2, which greatly outperforms the pure (Co₃O₄ and rivals the noble metal IrO₂ as benchmark OER electrocatalyst. Experimental results and theoretical calculations together demonstrate that Zn atoms doped at the surface of Zn-(Co₃O₄ electrode would be dissolved in the acidic electrolyte at the low anodic potentials, with cation vacancy generated for increasing the average oxidation state of adjacent Co^2+/3+ sites, and then accelerating the electrochemical surface reconstruction process to create high-valence Co⁴⁺ active sites for the improved acidic OER activity; while Zn atoms doped in the bulk of Zn-(Co₃O₄ electrode could serve as an electron donor for stabilizing the reconstructed Co⁴⁺ active sites, as well as upshift the d-band center of Co⁴⁺ active sites to strengthen the bonding with *O intermediates, reducing the energy barrier of rate-determining step (RDS) and thus boosting the intrinsic OER activity of Zn-(Co₃O₄ electrode. This work presents an alternative approach for regulating the reconstruction behavior of high-valence Co⁴⁺ active sites on (Co₃O₄ surface via foreign atom doping, and also inspires the development of non-noble metal-based electrocatalysts with high activity and long-term stability for PEMWE.