<p>Recent progress in advanced photocatalysis and photoelectrocatalysis has significantly expanded the frontier of solar energy conversion and environmental remediation. Driven by the urgent need for sustainable energy and green chemical processes, extensive efforts have focused on designing efficient semiconductor-based systems that can utilize a broader solar spectrum while enhancing charge separation and surface reaction kinetics. Strategies such as heterojunction engineering, elemental doping, cocatalyst loading, and defect modulation have emerged as effective means to tune band structures and suppress recombination losses. In parallel, the integration of photoactive materials into electrochemical architectures has given rise to photoelectrocatalysis, which couples photonic and electrical driving forces to achieve superior reaction rates and selectivity. Advanced characterization tools and computational modeling further enable mechanistic insights into charge transfer dynamics and active site functionality. Despite these advances, challenges persist regarding stability, scalability, and cost-effective synthesis. Continued innovations in material design, interfacial engineering, and system integration are anticipated to accelerate the transition of photocatalytic and photoelectrocatalytic technologies from laboratory research to practical applications in energy conversion, hydrogen production, and environmental remediation.</p>