W ₁₀ Single-Cluster-Mediated Syngas Electrosynthesis in Single-Sandwich-Layer ZnAl-Layered Double Hydroxide Catalysts

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 CO 2 reduction reaction (CO 2 RR). 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 = W 10, PW 12, and P 2 W 18 ) with abundant oxygen vacancies and zinc vacancies. The well-defined monodispersed W 10 clusters function as electron sponges for reversibly accepting and releasing electrons to boost the level of CO 2 reduction. The ZnAl-W 10 -3 can efficiently adjust HER and CO 2 RR to achieve a total Faradaic efficiency (FE) of 96.9% for both H 2 and CO production. A broad CO/H 2 ratio (0.32–1.35) can be obtained over the optimized ZnAl-W 10 -3 within a wide potential window (−0.8 to −2.0 V vs RHE) via adjusting the W 10 amount. Systematic investigations reveal that W 10 -mediated electron and proton transfer processes and abundant unsaturated sites in ultrathin ZnAl-LDH significantly enhance the tunability of the CO 2 RR and HER activities.