Alkaline earth metals induced electron transfer to Pt single-atom on carbon nitride toward boosting photocatalytic H₂ production

Regulating electronic configuration to fully exploit the potential of Pt single atoms for efficient photocatalytic hydrogen production is of great significance, but remains challenging. Herein, we report alkaline earth metals (AM) modified atomically dispersed Pt sites on graphitic carbon nitride (CN) for photocatalytic H₂ production. The results of XPS, XAFS and DFT calculation demonstrate that in these AMPt-CN (AM: Mg, Ca, Sr and Ba) catalysts, the incorporation of AM effectively increases the electron density of Pt single-atom and decreases the d-band center of Pt, concurrently reducing the free energy barrier for the hydrogen evolution reaction. Additionally, fs-TAS and photoelectric performance tests of catalysts reveal concurrent improvements in light absorption and charge separation efficiency with alkaline earth metal doping. Consequently, the optimized AMPt-CN achieve a remarkable hydrogen production rates of 2.79 (MgPt-CN), 1.55 (CaPt-CN), 2.12 (SrPt-CN) and 1.34 (BaPt-CN) mol g_Pt^-1 h^-1 with an high apparent quantum yield of 21.7%, 18.1%, 18.9% and 10.8%, respectively, superior to most of the reported carbon nitride based Pt single-atom catalysts. Noteworthily, together with energy band structure results, a prominent linear relationship between the hydrogen evolution activity and the corresponding conduction band potentials is established. These findings reveal a new perspective for in-depth comprehension of the role of alkaline earth metals in adjusting electronic properties of Pt single-atom catalysts for promoting photocatalytic performance.