Fabrication of a hollow-shaped CuO nanoparticle assembly using a sacrificial W₁₈O₄₉ template for...

Tungsten suboxide (W₁₈O₄₉) was used as a sacrificial template to prepare a hollow-shaped assembly of CuO nanoparticles as an active and stable catalyst for electrochemical CO₂ reduction. Catalyst precursor materials Cu-W₁₈O₄₉-x (x denotes the amount of Cu added; x = 0.1, 0.2, 0.5, 1, and 2) were prepared by the deposition of single-atomic Cu species on the surface of W₁₈O₄₉. In an alkaline electrolyte, the W₁₈O₄₉ phase gradually dissolved, and the single-atomic Cu sites aggregated into ultrasmall CuO particles with average sizes of 5-10 nm, which further formed a hollow-shaped assembly with high surface areas. The CuO nanoparticle assembly was found to be a good catalyst for the selective CO₂ reduction to C₂₊ products with a faradaic efficiency of up to 58% and a partial current density of up to 167 mA cm^-2.