Recent advances in piezo-photo heterojunction: a review on dual catalytic function for wastewater remediation and simultaneous hydrogen generation.

Water pollution and the energy crisis have become a persistent threat to modern civilization. Organic dyes, pharmaceuticals, pathogens, pesticides, fertilizers, etc., disrupt the ecological balance and create several health hazards to humankind. On the other hand, the depletion of non-renewable energy sources like coal, petroleum, etc., is also affecting modernization, the environment, and industrial production. In the last few decades, piezo catalysis and photocatalysis have emerged as successful and promising advanced oxidation processes to degrade such contaminants from wastewater and catalytic energy generation, like green H₂ evolution. The limitations, like high reaction time, recombination rate of photogenerated electron-hole pair, energy efficiency, etc., of such catalytic systems motivated the researchers to advance the systems by composite formation, metal ion implantation, heterostructure development, etc. This article delves into the piezo-photo heterostructure and its augmented multi-dynamic catalytic efficacy and green hydrogen generation. The sandwich structure of heterostructure enhances the catalytic performances by augmented reactive oxygen species (ROS) generation, lowering recombination rate, and enhancing the stability of the catalyst as well as H₂ evolution. This article also includes the underlying mechanism of mechanical stress-driven piezo-catalysis and photo-impulse-generated photocatalysis, and different types of heterostructure systems and their electronic structures. The fabrication strategies, operational conditions, and performance matrix of different types of heterostructures and their challenges in terms of stability, real-world applicability, and recent and future progress are also discussed in this article, which validates the environmental remediation and clean energy generation capability of this multifunctional system.