Harnessing hydrogen spillover: Biomimetic dual-site platinum-gold catalyst mimicking NAD+ -reducing hydrogenase

The hydrogen spillover phenomenon in heterogeneous catalysis shares similarities with the proton-coupled electron transfer (PCET) mechanism observed in natural enzymes. Drawing inspiration from these mechanisms, biomimetic dual-site platinum-gold (PtAu) catalyst was theoretical designed as a model to mimic the function of soluble NAD⁺-reducing hydrogenases (SH). This model catalyst facilitates efficient hydrogen oxidation and NAD⁺ reduction, offering potential applications in both bioelectrocatalysis and biosynthetic systems. In the design, Pt and Au simulated the NiFe and FMN active sites of SH, respectively, with hydrogen spillover serving as an alternative to the PCET mechanism. Experimental results and theoretical calculations revealed the individual contribution and synergistic interactions between Pt and Au, where Pt sites dissociated H₂ to produce active hydrogen which spontaneously spilled to neighboring Au sites for adsorbed NAD⁺ hydrogenation. In biocatalysis, PtAu catalyst exhibited superior NAD⁺ conversion efficiency and selectivity toward 1,4-NADH compared to previously reported Pt-based catalysts. In electrocatalysis, a H₂/O₂ enzymatic biofuel cell was constructed, achieving a maximum power output exceeding 2.0 mW cm⁻² while maintaining excellent operational stability. This mechanism-inspired strategy provided valuable insights into the understanding and design of catalysts, thereby offering greater potential for applications in replacing natural enzymatic catalysis.