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.
Zhang et al. (Tue,) studied this question.