Single atom doping induced charge-specific distribution of Cu1-TiO_(2) for selective aniline oxidation via a new mechanism

Utilizing single atom sites doping into metal oxides to modulate their intrinsic active sites,achieving precise selectivity control in complex organic reactions,is a highly desirable yet challenging endeavor.Meanwhile,identifying the active site also represents a significant obstacle,primarily due to the intricate electronic environment of single atom site doped metal oxide.Herein,a single atom Cu doped TiO_(2)catalyst(Cu_(1)-TiO_(2)) is prepared via a simple“colloid-acid treatment”strategy,which switches aniline oxidation selectivity of TiO_(2) from azoxybenzene to nitrosobenzene,without using additives or changing solvent,while other metal or nonmetal doped TiO_(2) did not possess.Comprehensive mechanistic investigations and DFT calculations unveil that Ti-O active site is responsible for triggering the aniline to form a new PhNOH intermediate,two PhNOH condense to azoxybenzene over TiO_(2) catalyst.As for Cu_(1)-TiO_(2),the charge-specific distribution between the isolated Cu and TiO_(2) generates unique Cu_(1)-O-Ti hybridization structure with nine catalytic active sites,eight of them make PhNOH take place spontaneous dissociation to produce nitrosobenzene.This work not only unveils a new mechanistic pathway featuring the PhNOH intermediate in aniline oxidation for the first time but also presents a novel approach for constructing single-atom doped metal oxides and exploring their intricate active sites.

Bonding Interaction of Adjacent Pt and Ag Single-Atom Pairs on Carbon Nitride Efficiently Promotes Photocatalytic H_(2)Production

Dual-atom catalysts(DACs)represent an exciting advance in the field of heterogeneous catalysis.They not only retain the beneficial characteristics of single-atom catalysts(SACs),but they also harness the synergistic effects that arise from the proximity of neighboring single-metal atoms.Nevertheless,the fabrication of heteronuclear dual-atom metals positioned adjacently for use in photocatalysis remains a significant challenge.Herein,we report the atomically dispersed adjacent Pt-Ag dual-atom pairs on carbon nitride(Pt1Ag1-a/CN)by a facile hydrogen-bonding assembly strategy via pyrolysis of the hydrogen-bonding supramolecule containing melamine-Ag and cyanuric acid-Pt complexes on carbon nitride(CN),through which the light absorption depressed by deposited carbonaceous materials during the preparation of dual-atom metals via a traditional method like the pyrolysis of the metal-organic framework.Thanks to the synergism achieved by the bonding interaction of adjacent Pt and Ag single-atom pairs,the developed Pt1Ag1-a/CN with 0.21%Pt loading shows a high turnover frequency(TOF)of 1115 h^(−1)with a H_(2)evolution rate(HER)of 12,000μmol g^(−1)h^(−1)for photocatalytic water splitting under simulated solar light irradiation(325 h^(−1)of TOF with 3480μmol g^(−1)h^(−1)of HER under visible light irradiation).This strategy outperforms the previously reported SACs on CN-based semiconductors.Density functional theory(DFT)calculations demonstrate that the adjacent Ag atom acts as a coordination atom to effectively regulate the electronic structure of the Pt atom and thus brings the d-band center of Pt close to the Fermi energy level,which is beneficial for the H_(2)production.This work presents a facile and general strategy for designing diverse adjacent diatomic cocatalysts in photocatalysis without depressing light absorption by the deposited carbon during the DAC preparation via previously reported methods.