Advances in Z-scheme semiconductor photocatalysts for the photoelectrochemical applications: A review

With continuous consumption of nonrenewable energy,solar energy has been predicted to play an essential role in meeting the energy demands and miti gating environmental issues in the future.Despite being green,clean and pollution-free energy,solar energy cannot be adopted directly as it cannot provide sufficiently high energy density to work in the absence of machinery.Thus,it is necessary to develop an effective strategy to convert and store solar energy into chemical energy to achieve social sustainable development using solar energy as the main power source.Photocatalysis,in which semi conductor photocatalysts play a key role,is one of the most promising can didates for realising the effective utilisation of sunlight in a green,low-cost and environmentally friendly method.The photocatalytic efficiency of photo catalysts is considerably influenced by their compositions.Among the various heterostructures,Z-scheme heterojunction is one of the most interesting ar chitecture due to its outstanding performance and excellent artificial imitation of photosynthesis.Z-scheme photocatalysts have attracted considerable at tention in the past few decades.Herein,we review contemporary Z-scheme systems,with a particular focus on mechanistic breakthroughs,and highlight current state-of-the-art systems.Z-type photocatalysts are classified as tradi tional,all-solid-state,direct Z-schemes and S-scheme photocatalysts.The morphology,characterisation and working mechanism of each type of Z-scheme are discussed in detail.Furthermore,the applications of Z-scheme in photoelectrochemical water splitting,nitrogen fixation,pollutant degrada tion and carbon dioxide reduction are illustrated.Finally,we outline the main challenges and potential advances in Z-scheme architectures,as well as their future development directions.