Photocatalysis for solar-driven reactions promises a bright future in addressing energy and environmental challenges. The performance of photocatalysis is highly dependent on the design of photocatalysts, which can be rationally tailored to achieve efficient light harvesting, promoted charge separation and transport, and accelerated surface reactions. Due to its unique feature, semiconductors with hollow structure offer many advantages in photocatalyst design including improved light scattering and harvesting, reduced distance for charge migration and directed charge separation, and abundant surface reactive sites of the shells. Herein, the relationship between hollow nanostructures and their photocatalytic performance are discussed. The advantages of hollow nanostructures are summarized as: 1) enhancement in the light harvesting through light scattering and slow photon effects; 2) suppression of charge recombination by reducing charge transfer distance and directing separation of charge carriers; and 3) acceleration of the surface reactions by increasing accessible surface areas for separating the redox reactions spatially. Toward the end of the review, some insights into the key challenges and perspectives of hollow structured photocatalysts are also discussed, with a good hope to shed light on further promoting the rapid progress of this dynamic research field.

Owing to the sluggish kinetics for water oxidation, severe surface charge recombination is a major energy loss that hinders efficient photoelectrochemical (PEC) water splitting. Herein, a simple process is developed for preparing a new type of low-cost iron-cobalt oxide (FeCoO x ) as an efficient co-catalyst to suppress the surface charge recombination on bismuth vanadate (BiVO 4 ) photoanodes. The new FeCoO x /BiVO 4 photoanode exhibits a high photocurrent density of 4.82 mA cm −2 at 1.23 V versus the reversible hydrogen electrode under AM 1.5 G illumination, which corresponds to >100% increase compared to that of the pristine BiVO 4 photoanode. The photoanode also demonstrates a high charge separation efficiency of ≈90% with excellent stability of over 10 h, indicating the excellent catalytic performance of FeCoO x in the PEC process. Density functional theory calculations and experimental studies reveal that the incorporation of Fe into CoO x generates abundant oxygen vacancies and forms a p-n heterojunction with BiVO 4 , which effectively promotes the hole transport/trapping from the BiVO 4 photocatalyst and reduces the overpotential for oxygen evolution reaction (OER), resulting in remarkably increased photocurrent densities and durability. This work demonstrates a feasible process for depositing cheap FeCoO x as an excellent OER cocatalyst on photoanodes for PEC water splitting.

Oxygen vacancy (VO) engineering is an effective method to tune the photoelectrochemical (PEC) performance, but the influence of VO on photoelectrodes is not well understood. Using hematite as a prototype, we herein report that VO functions in a more complicated way in PEC process than previously reported. Through a comprehensive analysis of the key charge transfer and surface reaction steps in PEC processes on a hematite photoanode, we clarify that VO can facilitate surface electrocatalytic processes while leading to severe interfacial recombination at the semiconductor/electrolyte (S‐E) interface, in addition to the well‐reported improvements in bulk conductivity. The improved bulk conductivity and surface catalysis are beneficial for bulk charge transfer and surface charge consumption while interfacial charge transfer deteriorates because of recombination through VO‐induced trap states at the S‐E interface.

Supporting information and the ORCID identification number(s) for the author(s) of this article can be found under: https://doi.Figure 4. a) The high-resolution XPS spectra of O 1s for TiO 2 and Nia/TiO 2 samples. b) Molecular models of O V on TiO 2 , O V on Ni/TiO 2 , and the corresponding formation energy of O V . c) Free energy versus the reaction coordinates of different active sites. The simulation is based on the (101) facet of anatase TiO 2 . d) The linear scan voltammetry curves of TiO 2 and Ni-a/TiO 2 based electrodes. Angewandte Chemie Communications 7233

Solar hydrogen conversion represents a clean and economic approach in addressing global energy and environmental issues, for which efficient photocatalysts have been heavily pursued. Lead halide perovskites are promising candidates for efficient phtocatalysts in solar hydrogen generation due to their attractive properties in light absorption, photo-generated charge transportation and utilization.However, photocatalytic applications of lead halide perovskites have been limited owing to their poor stability in the presence of water or other polar solvent environment. This work presents the rational control of surface ligands in achieving a good balance between stability and photocatalytic activity of CsPbBr 3 quantum dots (QDs). Detailed studies reveal that the deliberate surface ligands engineering is crucial for maximizing photocatalytic activity of CsPbBr 3 QDs while maintain good QD stability. A certain amount of surface ligands protect the CsPbBr 3 QDs from decomposition in moisture during the photocatalytic reaction while still enable efficient charge transfer for photocatalytic reactions on the surface of QDs. The well-controlled CsPbBr 3 photocatalyst shows efficient visible light-driven H 2 generation with outstanding stability (≥ 160h).