Molybdenum disulphide (MoS₂), with its active edge-sites, is a proposed alternative to platinum for catalyzing hydrogen evolution reaction (HER). Recently, the inert basal plane of MoS₂ was successfully activated and optimized with excellent intrinsic HER activity by creating and further straining sulphur (S)-vacancies. Nevertheless, little is known about the HER kinetics of those S-vacancies and the additional effects from elastic tensile strain. Herein, scanning electrochemical microscopy was used to determine the HER kinetic data for both unstrained S-vacancies (formal potential E⁰_v = -0.53 V_Ag/AgCl, electron-transfer coefficient α_v = 0.4, electron-transfer rate constant k⁰_v = 2.3 ×10^-4 cm/s) and strained S-vacancies (E⁰_sv = -0.53 V_Ag/AgCl, α_sv = 0.4, k⁰_sv = 1.0 ×10^-3 cm/s) on the basal plane of MoS₂ monolayers, and the strained S-vacancy has a four times higher electron-transfer rate than the unstrained S-vacancy. This study provides a general platform for measuring the kinetics of two-dimensional material-based catalysts.

Homogeneous photocatalysis has considerably contributed to green applications such as energy production and environmental decontamination. Currently, researchers mainly focus on the search for sustainable processes that can generate valuable chemical compounds with high selectivity and aid in the complete mineralization of hazardous compounds. Although homogeneous photocatalysts exhibit superior performance, their recovery after the reaction is difficult. The 3Rs process, i.e., recovery, recycling and reuse of photocatalysts respectively, is critical to make a photocatalytic process eco-friendly. Heterogenization of homogeneous photocatalysts is considered as an effective method to not only realize the recycling of homogeneous photocatalysts, but also enhance the overall photocatalytic activity. Conventional methods have employed synthetic materials for the heterogenization of homogeneous photocatalysts. Nevertheless, scientists have discovered that natural polymer sources can be alternatives due to their excellent chemical, mechanical, and electrical properties for applications under harsh reaction conditions. In this review, we have summarized state-of-the-art techniques employed for the heterogenization of homogeneous photocatalysts using various supporting materials in terms of design and preparation. First, we have organized these strategies into different categories, such as microporous encapsulation, dye-sensitized semiconductors, metal–organic framework (MOF) construction, carbon material fixation, synthetic polymer attachment and natural origin supports. To provide readers with deeper insights into this field, we have presented some fundamentals of homogeneous photocatalysis with respect to environmental applications and its heterogeneous strategies. Furthermore, we have discussed the performance of heterogeneous photocatalysts prepared from these methods, including photocatalytic performance, product selectivity and reusability. Finally, we have concluded with different aspects on the current challenges and new aspects in emerging technologies.

Halide perovskites (HPs), renowned for their intriguing optoelectronic properties, such as robust light absorption coefficient, long charge transfer distance, and tunable band structure, have emerged as a focal point in the field of photocatalysis. However, the photocatalytic performance of HPs is still inhibited by rapid charge recombination, insufficient band potential energy, and limited number of surface active sites. To overcome these limitations, the integration of two-dimensional (2D) materials, characterized by shortened charge transfer pathways and expansive surface areas, into HP/2D heterostructures presents a promising avenue to achieve exceptional interfacial properties, including extensive light absorption, efficient charge separation and transfer, energetic redox capacity, and adjustable surface characteristics. Herein, a comprehensive review delving into fundamentals, interfacial engineering, and charge carrier dynamics of HP/2D material heterostructures is presented. Numerous HP/2D material photocatalysts fabricated through diverse strategies and interfacial architectures are systematically described and categorized. More importantly, the enhanced charge carrier dynamics and surface properties of the HP/2D material heterostructures are thoroughly investigated and discussed. Finally, an analysis of the challenges faced in the development of HP/2D photocatalysts, alongside insightful recommendations for potential strategies to overcome these barriers, is provided.

The review summarizes various post-synthetic treatments reported in the past five years, including chemical treatments, electrochemical and irradiation-based treatments, and post-annealing treatments, for PEC water splitting application.