Modulation strategies in titania photocatalyst for energy recovery and environmental remediation

Among the various renewable sources of energy, solar energy is the most abundant and cleanest which can fulfill all our future energy demand. However, the stochastic nature of solar radiation hinders the continual utilization of that abundant energy. The strategic and effective usages of semiconductor-based photocatalysis can efficiently use this energy in different forms. Researchers have put great interest toward designing and constructing a highly efficient semiconductor photocatalyst to promote its real-life application potential to capture and utilize solar energy. It is very crucial to summarize the basics and advanced strategies to design and construct a semiconductor-based photocatalyst system. Herein, we have reviewed and summarized the state-of-the-art strategies and their basics to improve the photocatalytic activity of TiO2 in two aspects: (i) environmental remediation, and (ii) energy conversion. This review article focuses and answer three major queries of the reader i.e. (i) how to enhance and broaden the solar-light absorption range, (ii) how to design more surface-active sites, and (iii) how to slow down or inhibit the recombination of photogenerated charge carriers to promote the photocatalytic efficiency. Hence, this review article will give comprehensive knowledge of the design and construction of the TiO2 based photocatalyst and boost its efficiency towards energy recovery (CO2 conversion, N-2 fixation, and H-2 evolution), and environmental remediation (pollutant degradation, NOx conversion, and bacterial disinfection).