Ultra-low palladium single-atom catalysts enabled by strong metal support interactions for high-efficiency methanol steam reforming

Although methanol steam reforming (MSR) is industrialized, Cu sintering and spontaneous combustion pose challenges for applications in automotive, marine, and military sectors. To address these, a small amount of Zr (Zn/Zr = 5:1) was introduced during ZnO synthesis, creating a heterostructure that increases surface area and pore volume, thereby enhancing Pd atom dispersion. The heterostructure improves active phase dispersion and strengthens interactions between Pd single atoms and the support, inducing electron transfer from Pd to the support. As a result, an electron-deficient Pd configuration promotes HCOO* intermediate formation, reducing carbon monoxide (CO) accumulation. The 0.1 % Pd/Zn 5 -Zr 1 catalyst (with a Pd content of 1000 ppm) exhibits a hydrogen (H 2 ) production rate of 1146.8 mol·g Pd −1 ·h −1 , achieving 93.3 % methanol conversion and 95.7 % carbon dioxide (CO 2 ) selectivity. Compared to the 3 % Pd/ZnO catalyst from prior work, Pd loading is reduced by 30 times, significantly improving utilization efficiency. Comprehensive characterization, performance evaluations, and theoretical calculations suggest that the heterostructure of ZnO-ZrO 2 facilitates excellent hydrogen productivity and selectivity, with atomic Pd playing a crucial role in methanol dissociation. Regulating the electronic environment of Pd and optimizing its interaction with the support are identified as key factors in designing high-performance catalysts.