Recent advances in TiO2 nanotube arrays-based composites for photoelectrochemical water splitting and environmental remediation

Sunlight-driven photocatalysis offers a promising approach to simultaneously and sustainably address environmental pollution and energy challenges. Among the various photocatalysts, TiO 2 nanotube arrays (TNTAs) have gained prominence owing to their distinctive structural configuration, large surface area, rapid electron transport, and adjustable morphology. However, owing to the intrinsic bandgap limitations of TiO 2 , modifications are required to enhance its photocatalytic efficiency. This review article provides a comprehensive overview of the formation of TNTAs on various substrates and explores their modification for applications in photoelectrochemical (PEC) water splitting and environmental remediation. The mechanisms of photocatalysis and PEC reactions, along with strategies for electronic structure engineering are discussed. The manuscript systematically evaluates the primary synthesis approaches for TNTAs, including electrochemical anodization, hydrothermal, sol–gel, and template‑assisted methods. Recent developments in the growth of TNTAs on different substrates are presented, covering pristine titanium and modified TNTAs incorporating metals, metal oxides, semiconductors, and carbon materials as well as Ti‑based binary alloys and other substrates. In addition, recent applications in water splitting and environmental remediation consisting of the degradation of organic dyes, the photoreduction of heavy metal ions, and the elimination of gaseous pollutants of these TNTAs-based substrate are comprehensively described, Research gaps are discussed, and the challenges and prospects for the use of TNTAs are highlighted. This review aims to provide insights toward a better understanding of TNTA-based composites and their future applications as efficient photocatalysts.