Valence state effect of Cu on photocatalytic CO_(2)reduction

Copper(Cu)is extensively employed in photocatalytic CO_(2)reduction reactions for the production of high-value products.The valence state of transition metals plays a pivotal role in influencing the catalytic process.However,due to the complex valence state changes of Cu in the CO_(2)reduction reaction,research on its valence state effect is lacking.The current work is to prepare a series of TiO_(2)/CuX with stable Cu valence composition using different copper halides(CuX and CuX_(2),X=Br or Cl)as precursors.The results show that the CuBr_(2)loading leads to Cu^(+)/Cu^(2+) mixed cocatalyst and exhibits the highest activity for CO_(2)photoreduction.The CH4 evolution rate of the TiO_(2)/CuBr_(2)catalyst is as high as 100.59μmol h^(-1)g^(-1),which is 6.6 times that of pristine TiO_(2).The CH4 selectivity reaches 77%.The enhanced catalytic activity and selectivity can be ascribed to the efficient surface adsorption,activation,excellent carrier separation,and transfer ofCu^(+)/Cu^(2+) mixed cocatalyst.Our findings provide a reference for designing highly active Cu-based photocatalysts.

Bifunctional core–shell co-catalyst for boosting photocatalytic CO_(2) reduction to CH_(4)

Solar-light-driven CO_(2) reduction CO to CH_(4) and C2H6 is a complex process involving multiple elementary reactions and energy barriers.Therefore,achieving high CH_(4) activity and selectivity remains a significant challenge.Here,we integrate bifunctional Cu2O and Cu-MOF(MOF=metal-organic framework)core–shell co-catalysts(Cu2O@Cu-MOF)with semiconductor TiO_(2).Experiments and theoretical calculations demonstrate that Cu2O(Cu+facilitates charge separation)and Cu-MOF(Cu2+improves the CO_(2) adsorption and activation)in the core–shell structure have a synergistic effect on photocatalytic CO_(2) reduction,reducing the formation barrier of the key intermediate*COOH and*CHO.The photocatalyst exhibits high CH_(4) yield(366.0μmol·g^(-1)·h^(-1)),efficient electron transfer(3283μmol·g^(-1)·h^(-1))and hydrocarbon selectivity(95.5%),which represents the highest activity of Cu-MOF-based catalysts in photocatalytic CO_(2) reduction reaction.This work provides a strategy for designing efficient photocatalysts from the perspective of precise regulation of components.

Pt-surface oxygen vacancies coupling accelerated photo-charge extraction and activated hydrogen evolution

Semiconductors-based heterogeneous photocatalytic water splitting has been extensively studied,but it still remains challenging to accelerate the separation of electron-hole pairs and facilitate the reaction kinetics.Here we report a general strategy to fabricate highly efficient Pt/TiO_(2)photocatalyst by coupling the Pt co-catalysts and surface oxygen vacancies(VO)of TiO_(2).TiO_(2)was pre-modified with alkali or alkaline earth metals ion solutions,which produce a large number of surface hydroxyl on TiO_(2).Subsequently,the photodeposited Pt sub-nanoparticles substitute surface hydroxyl and induce surface VO on TiO_(2).The coupling of Pt and surface VO on TiO_(2)can accelerate the extraction of photo-charges through the interaction of Pt-VO-Ti bonds and reduce the hydrogen evolution barrier,thereby promoting the photocatalytic activity.The synthesized Pt-VO-TiO_(2)sample exhibits a photocatalytic hydrogen evolution activity as high as 1.5 L·g^(−1)·h^(−1),which is 2.2 times that of traditional Pt/TiO_(2).Our findings indepth understand the synergistic effect of co-catalysts and defects on photocatalysis and open up new possibilities for achieving robust photocatalytic water splitting.