Mutual-modification effect in adjacent Pt nanoparticles and single atoms with sub-nanometer inter-site distances to boost photocatalytic hydrogen evolution

The proximity effect of adjacent metal sites has been widely investigated to modulate the electronic structure and catalytic activity of single atoms (SAs) catalysts, but is rarely reported between bicomponent metal nanoparticles (NPs) and SAs. Herein, we report an atom-like Pt@PtSAs co-catalyst on polymeric carbon nitride nanosheets (PCNS), where the mutual-modification effect exists in nucleus-like Pt NPs and diffuse PtSAs with sub-nanometer inter-site distances (Pt@PtSAs) to enhance the catalytic activities. The adjacent Pt NPs and PtSAs act as the modulators to tailor the d-band electronic states of each other through strong electronic metal-support interaction (EMSI) at PtSAs-PCNS-Pt NPs interface, resulting in enhanced intrinsic H₂ evolution activity of Pt@PtSAs sites. The EMSI also accelerates photoexcited electron transfer from PCNS to Pt@PtSAs sites to participate in H₂ evolution reaction. Consequently, the Pt@PtSAs-decorated PCNS exhibits an unexpectedly photocatalytic H₂ evolution rate up to 15.75 mmol g^-1 h^-1 under visible light, 1.9 times higher than that of PtSAs-decorated PCNS. This work sheds light on the synergistic mechanism among metal NPs and SAs and provides a valuable strategy to design highly efficient photocatalysts.