To address the energy crisis and environmental problems, the applications of solar energy have received intensive attention. Converting solar energy to hydrogen using a photoelectrochemical (PEC) cell is one of the most promising approaches to meet future energy demands. As an earth abundant metal oxide, tungsten trioxide (WO3), which has a moderate band gap (2.5–2.7 eV), ideal valence band position, and high resistance to photocorrosion, has been widely utilized in PEC photoanodes. To obtain a WO3 photoanode with high PEC efficiency, tremendous efforts have been made to improve the light absorption capacity, charge carrier dynamics, and oxygen evolution activity. In this report, the recent advances in WO3 photoanode optimization, including morphology design, dopants doping, heterojunction fabrication, and surface modification are summarized. In this review, these developments and representative applications of WO3 photoanodes in unassisted water splitting devices are also discussed. Finally, perspectives on the significant challenges and future prospects for the development of WO3 photoanodes for PEC water splitting are provided.

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The surface plasmon polariton (SPP) at an interface between a metal and a uniaxial crystal is studied. A new class of hybridized SPP found in this work is quite different from the traditional SPP at the interface between a metal and an isotropic dielectric. In contrast to the two evanescent fields for the traditional SPP, the hybridized SPP involves four evanescent fields: transverse-electric-like and transverse-magnetic-like waves in the metal, and ordinary-light-like and extraordinary-light-like waves in the uniaxial crystal. The necessary conditions and the regimes for the existence of the hybridized SPP are presented. Some potential applications are also discussed.

Pb-free inorganic–organic perovskite materials - C10H12N2MnBr4 (compound 1) and C5H6NMnBr3 (compound 2) - with different structures were obtained by using pyridine and manganese bromide as raw materials. The single-crystal X-ray diffraction analyses revealed their different lattices in space groups. Compound 1 - Mn tetra-Br-coordinated with two pyridines - presented an isolated mononuclear structure. Its temperature-dependent photoluminescence spectra exhibited an emission band at 523 nm from the lowest d–d crystal field transition of Mn and a higher energy emission at 493 nm from its vibronic state at low temperature. Compound 2 - Mn octahedra-Br-coordinated with a minor pyridine - face-shares with linear chains, which were separated by pyridine molecules. Its emission peak occurred at around 650 nm, in which ferromagnetism was observed. The lifetimes of d–d transition for a single manganese ion and the Mn cluster were presented.

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