Cadmium sulfide is a potential candidate for photocatalytic water splitting. However, CdS nanoparticles have a high recombination rate of photoinduced carriers induced by aggregation. Therefore, decreasing the recombination rate and increasing the migration rate of photogenerated carriers are essential to drive the development and application of CdS in hydrogen production. In this study, we design CdS with a three-dimensional ordered macroporous (3DOM) structure using polymethylmethacrylate as a template. It not only retains the excellent visible light response of CdS but also improves the easy recombination of photogenerated carriers in CdS nanoparticles by taking advantage of the unique ability of mass transfer, charge separation, and migration in the 3DOM structure. Meanwhile, the highly ordered periodic structure of 3DOM CdS can produce a slow photon effect of photonic crystals to obtain more photoinduced carriers. In particular, we found that a suitable stop-band position is beneficial to maximize the utilization of the slow photon effect. The photocatalytic hydrogen evolution rate of Pt–CdS is considerably improved after constructing the 3DOM structure. This study provides a new design strategy of ordered macroporous sulfide catalysts to achieve high photocatalytic activity.

Heterostructures constructed by conventional methods, particularly those randomly distributed manner on the catalyst surface as well as forming core−shell structures, lead to imbalance in carrier utilization, limitation of charge extraction/transfer, and hindrance of light harvesting. In this study, we constructed a new type of heterostructure consisting of alternate CdS and ZnO grains bridged with good interfaces in the hierarchically periodic macroporous (HPM) walls by the pyrolysis of CdZnS solid solution in a polymethyl methacrylate nanoreactor. Since the alternately arranged CdS−ZnO heterojunctions in the HPM form multiple quantum well-like (MQW-like) band alignments that favor the Z-scheme charge transfer, the photogenerated electrons and holes are spatially separate and accumulated on CdS and ZnO parts, respectively. Besides the desirable spatial separation of the photogenerated charges, the enabled excellent mass transfer in the macroporous structures effectively accelerates the utilization of the carriers. Owing to the synergistic effect of the MQW-like band alignments and the HPM structures, the photocatalytic H 2 evolution rate of HPM CdS−ZnO is as high as 587.8 μmol h −1 without a cocatalyst. This work introduces a fascinating strategy for the creation of alternate heterojunctions to improve carrier utilization.

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Photocatalytic technology has made a series of breakthroughs in environmental remediation, but the degradation performance of persistent heavy metal ions and organic pollutants is not particularly excellent. In addition, the layered structure of bismuth oxyhalides (BiOX, X = I, Br, and Cl) has been a popular material for photodegradation and photoelectrochemistry. Accordingly, with a view to construct a suitable band structure and control the surface structure, it is necessary to develop a strategy to synthesize a BiOCl 1−x I n solid solution with halogen vacancies. In this study, halogen vacancies are in situ introduced into the BiOCl 1−x I n solid solution through constructing chemical bonds between the hydroxyl groups in glycerol and the I ions during the growth process. The band of the halogen-vacancy BiOCl 1−x I n solid solution is widened and active sites centered at halogen vacancies are formed in the direction favorable for the photocatalytic reaction, resulting in enhanced performance in the reduction of Cr(VI) and the oxidation of phenol. The results obtained can provide a new idea for the design of efficient photocatalysts by controlling the formation of halogen vacancies.

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