Cobalt-Based Cocatalysts for Photocatalytic CO_(2)Reduction

Conversion of carbon dioxide(CO_(2))into valuable chemicals and renewable fuels via photocatalysis represents an eco-friendly route to achieve the goal of carbon neutralization.Although various types of semiconductor materials have been intensively explored,some severe issues,such as rapid charge recombination and sluggish redox reaction kinetics,remain.In this regard,cocatalyst modifi cation by trapping charges and boosting surface reactions is one of the most effi cient strategies to improve the effi ciency of semiconductor photocatalysts.This review focuses on recent advances in CO_(2)photoreduction over costeff ective and earth-abundant cobalt(Co)-based cocatalysts,which are competitive candidates of noble metals for practical applications.First,the functions of Co-based cocatalysts for promoting photocatalytic CO_(2)reduction are briefl y discussed.Then,diff erent kinds of Co-based cocatalysts,including cobalt oxides and hydroxides,cobalt nitrides and phosphides,cobalt sulfi des and selenides,Co single-atom,and Co-based metal–organic frameworks(MOFs),are summarized.The underlying mechanisms of these Co-based cocatalysts for facilitating CO_(2)adsorption–activation,boosting charge separation,and modulating intermediate formation are discussed in detail based on experimental characterizations and density functional theory calculations.In addition,the suppression of the competing hydrogen evolution reaction using Co-based cocatalysts to promote the product selectivity of CO_(2)reduction is highlighted in some selected examples.Finally,the challenges and future perspectives on constructing more effi cient Co-based cocatalysts for practical applications are proposed.

Ultrathin ZnIn_(2)S_(4)Nanosheets-Supported Metallic Ni_(3)FeN for Photocatalytic Coupled Selective Alcohol Oxidation and H_(2)Evolution

Photocatalytic anaerobic organic oxidation coupled with H_(2)evolution represents an advanced solar energy utilization strategy for the coproduction of clean fuel and fine chemicals.To achieve a high conversion efficiency,the smart design of efficient catalysts by the right combination of semiconductor light harvesters and cocatalyst is highly required.Herein,we report a composite photocatalyst composed of noble metal-free transition metal nitride Ni_(3)FeN decorated on 2D ultrathin ZnIn_(2)S_(4)(ZIS)nanosheets for selective oxidation of aromatic alcohols to aldehydes pairing with H_(2)production.In the composite,ultrathin ZIS serves as a light harvester that greatly shortens the diffusion length of photogenerated charges,while the metallic nitride Ni_(3)FeN acts as an advanced cocatalyst which not only captures the photoelectrons generated from the ultrathin ZIS to promote the charge separation,but also provides active sites to lower the overpotential and accelerate the H_(2)reduction.The best photocatalytic performance is found on ZIS/1.5%M-Ni_(3)FeN,which shows a H_(2)generation rate of 2427.9μmol g^(^(-1))h^(-1)and a benzaldehyde(BAD)production rate of 2460μmol g^(-1)h^(-1),about 7.8-fold as high as that of bare ZIS.This work is anticipated to endorse the exploration of transition metal nitrides as high-performance cocatalysts to promote the coupled photocatalytic organic transformation and H_(2)production.