Revealing the Principle of Progressively Enhanced Photocatalytic Reactivity in Dual Single-Atoms-Mediated Electronic...

In this work, a CdTe@TiO₂ single atoms (SAs) catalysts is successfully synthesized, realizing unique portion of nonbonding oxygen-coordinated configuration of Cd─O─Te dimers coupling. Astonishingly, the 5th CdTe@TiO₂ (0.027 min^-1) shows progressively augmenting phenomenon, accompanied with 2.73 times higher than that of fresh CdTe@TiO₂ (0.010 min^-1) on the photocatalytic rate constant of gaseous toluene conversion. The incrementally enhanced photocatalytic activity is attributed to atomically dispersed Cd/Te SAs sites generation during the photoreduction process, and further leading to the optimized electron interactions between Cd, Te atoms, and TiO₂ NTs and causing a positive shift in the d-band center closer to the Fermi level. Density Functional Theory (DFT) calculations reveal that this unique Cd/Te SAs increasing phenomenon can mutually elevate the electronic density around Cd/Te SAs and generate a substantial local electric field at the interface. In essence, the free energy barriers of the benzene intermediates ring-opening as the rate-determining step appeared to significantly diminish tendency from 1.10 to 0.96 eV, in line with the ICOHP calculation of Cd/Te─O bonds in TS promoted from -2.43 to -3.49 eV. This work unearths the mechanism for ascendant electronic states of synergies dual-metal sites, providing a versatile strategy to tailor the SAs catalysts for solar energy conversion.