Interfacial engineering insights of promising monolayer 2D Ti3C2 MXene anchored flake-like ZnO thin films for improved PEC water splitting

Abstract

This work explores the development of novel monolayer-structured 2D Ti3C2 MXene anchored flake-like ZnO thin films (Ti3C2/ZnO and ZnO/Ti3C2) for achieving superior photoelectrochemical (PEC) water splitting activity. Specifically, swapping of Ti3C2 position at the interface of ZnO strongly influenced the charge carrier generation and separation. Taking the advantage of Ti3C2 MXene (electron trapping effect), Ti3C2 MXene interfacially anchored on the ZnO surface (ZnO/Ti3C2) achieved superior charge carrier separation compared to the Ti3C2 developed under the ZnO (Ti3C2/ZnO). Structural studies confirmed the growth of predominant Ti3C2 (002) reflection along with ZnO (002) and relative variation in the peak intensity, which revealed the role of Ti3C2 position in the resultant Ti3C2/ZnO and ZnO/Ti3C2. XPS studies revealed the role of Ti3C2 at the interface of ZnO. Moreover, surface morphological features demonstrated the successful interfacial interaction between monolayer Ti3C2 and flake-like ZnO. Interestingly, ZnO/Ti3C2 prevailed superior hydrophilic nature with water a contact angle of 42° compared to pure ZnO (85°) and Ti3C2/ZnO (56°). As a result, ZnO/Ti3C2 promoted superior optical absorption with a reduced band gap of 3.10 eV. As evidenced from the above features, ZnO/Ti3C2 achieved photoconversion efficiency about 0.175% at +0.6 V, which suggests the electron trapping effect of Ti3C2 MXene on ZnO. In a word, swapping of Ti3C2 MXene position at the interface of ZnO is an effective way to explore the electron trapping effect of Ti3C2 MXene and charge carrier separation for achieving superior PEC water splitting activity. © 2021 Elsevier B.V.