Tunable wettability on metal oxide surfaces for future applications

Metal oxides (MOs) as a class of indispensable materials in many industrial products have been extensively investigated for a wide range of applications, including energy and environment-related fields. In the applications of MOs, the surface wettability exhibits significant influences on their properties. Hence, the regulation of wettability on MO surfaces with desired surfaces is essential to realize the target properties in various practical applications. In this review, we first present some principal theories of surface wettability and then give a detailed introduction on the synthesis of superhydrophobic and superhydrophilic MO surfaces. Particularly, two primary strategies, including micro-/nano-structures construction and surface modification, for building superhydrophobic MO surfaces are summarized. Next, the smart stimuli-response MO surfaces, which deliver switchable wettability under some external stimulus, and the strategies for achieving reversible wettability transition are highlighted. Subsequently, a comprehensive review is given on the wettability-related application fields of MO surfaces. Finally, the current challenges for surface construction and reversible transitions are critically analyzed, and four future research directions are pointed out in order to offer some constructive clues for the future manipulation and applications of MO surfaces.