Recent advances in TiO2 nanotube arrays-based electrocatalysts for electrochemical water splitting and CO2 reduction

Abstract

Self-organized titanium oxide nanotube arrays (TNTs) have attracted considerable attention as a promising semiconductor substrate for water splitting due to their unique properties, including high electron mobility, large surface area, and strong mechanical stability. This has prompted extensive research efforts focused on the fabrication structure and enhancement of the electronic characteristics, structure modification, and applications of these one-dimensional substrates as TNT-based electrocatalysts. This review comprehensively addresses all these topics, which were not previously covered. It begins with the preparation techniques, modification strategies of TNTs, and the formation of TNT factors, elaborating on each in depth. The review also discusses the chemical and physical properties of TNTs, the fundamental principles of the electrocatalytic process using TNTs, and their application in water electrolysis and CO₂ reduction. The main electrocatalytic potential of TNTs, including hydrogen and oxygen gas generation, is discussed extensively, considering the reported experiments conducted in the last decade. For example, 1D TNTs supported PtOx nanoclusters were studied as a more effective electrocatalyst for the hydrogen evolution reaction, achieving an overpotential of -30 mV to produce -10 mA cm⁻². Thus, the PtOx/TNTs electrocatalyst was superior to that of PtOx loaded on TiO₂ nanoparticles and the benchmark electrode (Pt/C). This outstanding activity can be attributed to the strong interaction between the TNTs and the Pt nanoclusters. This review aims to enhance understanding of TNT-based nanostructured materials and their potential applications as effective substrates in electrocatalytic processes. The challenges of using conductive or semiconductor support for loading the co-catalyst in the future include the need for it to be low-cost, robust, scalable, and sustainable; however, titanium oxide nanotubes (TNTs) can address all of these challenges and pave the way for long-term sustainable energy applications.

Graphical abstract