W₁₀ Single-Cluster-Mediated Syngas Electrosynthesis in Single-Sandwich-Layer ZnAl-Layered Double Hydroxide Catalysts.

Abstract

Syngas electrosynthesis stands as an energy-saving strategy for producing chemical raw materials, but it remains a great challenge in achieving a balance between the hydrogen evolution reaction (HER) and the CO₂ reduction reaction (CO₂RR). Herein, a series of single-cluster catalysts (SCCs) were constructed by uniformly dispersing different polyoxometalates (POMs) into ZnAl-layered double hydroxide (ZnAl-LDH) through a simple stripping self-assembly technique, forming single-sandwich-layer-based ZnAl-POM (POM = W₁₀, PW₁₂, and P₂W₁₈) with abundant oxygen vacancies and zinc vacancies. The well-defined monodispersed W₁₀ clusters function as electron sponges for reversibly accepting and releasing electrons to boost the level of CO₂ reduction. The ZnAl-W₁₀-3 can efficiently adjust HER and CO₂RR to achieve a total Faradaic efficiency (FE) of 96.9% for both H₂ and CO production. A broad CO/H₂ ratio (0.32-1.35) can be obtained over the optimized ZnAl-W₁₀-3 within a wide potential window (-0.8 to -2.0 V vs RHE) via adjusting the W₁₀ amount. Systematic investigations reveal that W₁₀-mediated electron and proton transfer processes and abundant unsaturated sites in ultrathin ZnAl-LDH significantly enhance the tunability of the CO₂RR and HER activities.