Next-generation photoelectrocatalysts: Real-time characterization and applications in sustainable energy and environment

The twin global challenges of energy scarcity and environmental pollution call for innovative and sustainable technological solutions. Photoelectrocatalysis has emerged as a promising strategy for solar-driven water splitting and environmental remediation, offering an eco-friendly route for hydrogen production and pollutant degradation. At the heart of this progress are hybrid catalysts, which integrate multiple material components to synergistically enhance light absorption, charge separation, and catalytic efficiency. However, optimizing these intricate systems requires a thorough understanding of their behaviour under real-world operating conditions. This review provides a critical overview of the design principles, classifications, and synthesis methods of hybrid photoelectrocatalysts, with particular attention to their applications in water splitting and environmental cleanup. Special emphasis is placed on the use of real-time (in-situ and operando) spectroscopic techniques such as X-ray absorption, Raman, Mössbauer and transient absorption spectroscopies, which offer vital insights into active sites, reaction intermediates, and structure–performance relationships. These advanced tools are essential for guiding the rational design of catalysts and enhancing their durability. We also address current challenges, including issues of material stability and the intricacies of real-time analysis, and highlight emerging directions such as artificial intelligence-driven catalyst discovery and the integration of multiple spectroscopic methods. By bridging materials engineering with mechanistic insight, this review outlines a roadmap for developing next-generation photoelectrocatalysts aimed at scalable, sustainable solutions for energy and environmental needs.