Design and applications of hollow materials for photocatalytic H2 evolution and CO2 reduction

With the rapid development of global economy, an increasing energy and environmental problems have been appeared, such as energy shortage, global warming, air contamination et al. It has been reported that reducing the energy demand is a key mechanism for climate change but is not practical for economic growing especially in lower-income parts. Photocatalytic technology has attracted abundant attention including water splitting, CO₂ reduction, N₂ fixation and degradation of pollutants. Especially photocatalytic water splitting driven by solar energy and photocatalytic CO₂ reduction can obtain useful chemical products, which both can convert solar energy into storable and transportable chemical energy resource. Influenced by the Fujishima - Honda pioneers work in 1972, a variety of semiconductors-based photocatalysts have been developed by the researchers including metal oxide (CeO₂, TiO₂ , ZnO and perovskite oxide photocatalysts), transition metal sulfides (CdS, Zn_xCd_1-xS, ZnIn₂S₄, Mn_xCd_1-xS) and nitrides (g-C₃N₄，TiN). However, the pristine photocatalysts suffer from the low energy conversion efficiency and weak stability especially sulfides, such as CdS or Zn_xCd_1-xS, which can be ascribed to the reason that the S^2- is easily oxidized by the photogenerated holes on the valence band.

Generally, the inferior activity is mainly restricted by the following factors: 1) the insufficient light absorption; 2) high photogenerated electron-hole pairs’ recombination rate; 3) sluggish surface reaction kinetics. A variety of strategies have been reported to promote the photocatalytic performance of the semiconductor materials such as morphology control, element doping, construction of junctions, and decoration of cocatalysts, and so on.

As we all know, the performance is closely related to the structures of substances. In the recent years, hollow structured materials have attracted abundant attention for the application of energy conversion field due to their merits of large specific surface area, improved light absorption and shortened charge carriers transfer path. With the inner and outer surfaces of hollow structured materials, they can provide a superior platform to deposit other components. Therefore, numbers of hollow hierarchical systems have been designed and fabricated over the latest decades. It is significant to rationally design and construct complex hierarchical structures.

Recently, a research team led by Prof. Lei Ge from China University of Petroleum Beijing reported a review about design and applications of hollow structured nanomaterials for photocatalytic H₂ evolution and CO₂ reduction. They presented the general preparation approaches of hollow materials. Afterwards, they summarized the synthesis method and mechanism of the recent typical hollow structured materials for the application of photocatalytic field. Moreover, the complex hollow structured hierarchical photocatalysts have been classified into two sections including hollow cocatalysts-based and hollow host photocatalysts-based materials. The design principle and the analysis of photocatalytic reaction mechanism for photocatalytic H₂ evolution and CO₂ reduction have also been introduced. The effect of hollow materials has also been involved. This review can provide reference in the ration design of advanced high-performance photocatalytic materials. The results were published in Chinese Journal of Catalysis (https://doi.org/10.1016/S1872-2067(21)63863-9).

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About the Journal

Chinese Journal of Catalysis is co-sponsored by Dalian Institute of Chemical Physics, Chinese Academy of Sciences and Chinese Chemical Society, and it is currently published by Elsevier group. This monthly journal publishes in English timely contributions of original and rigorously reviewed manuscripts covering all areas of catalysis. The journal publishes Reviews, Accounts, Communications, Articles, Highlights, Perspectives, and Viewpoints of highly scientific values that help understanding and defining of new concepts in both fundamental issues and practical applications of catalysis. Chinese Journal of Catalysis ranks among the top six journals in Applied Chemistry with a current SCI impact factor of 8.271. The Editors-in-Chief are Profs. Can Li and Tao Zhang.

At Elsevier http://www.journals.elsevier.com/chinese-journal-of-catalysis

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