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 Ti 3 C 2 MXene anchored flake-like ZnO thin films (Ti 3 C 2 /ZnO and ZnO/Ti 3 C 2 ) for achieving superior photoelectrochemical (PEC) water splitting activity. Specifically, swapping of Ti 3 C 2 position at the interface of ZnO strongly influenced the charge carrier generation and separation. Taking the advantage of Ti 3 C 2 MXene (electron trapping effect), Ti 3 C 2 MXene interfacially anchored on the ZnO surface (ZnO/Ti 3 C 2 ) achieved superior charge carrier separation compared to the Ti 3 C 2 developed under the ZnO (Ti 3 C 2 /ZnO). Structural studies confirmed the growth of predominant Ti 3 C 2 (002) reflection along with ZnO (002) and relative variation in the peak intensity, which revealed the role of Ti 3 C 2 position in the resultant Ti 3 C 2 /ZnO and ZnO/Ti 3 C 2 . XPS studies revealed the role of Ti 3 C 2 at the interface of ZnO. Moreover, surface morphological features demonstrated the successful interfacial interaction between monolayer Ti 3 C 2 and flake-like ZnO. Interestingly, ZnO/Ti 3 C 2 prevailed superior hydrophilic nature with water a contact angle of 42° compared to pure ZnO (85°) and Ti 3 C 2 /ZnO (56°). As a result, ZnO/Ti 3 C 2 promoted superior optical absorption with a reduced band gap of 3.10 eV. As evidenced from the above features, ZnO/Ti 3 C 2 achieved photoconversion efficiency about 0.175% at +0.6 V, which suggests the electron trapping effect of Ti 3 C 2 MXene on ZnO. In a word, swapping of Ti 3 C 2 MXene position at the interface of ZnO is an effective way to explore the electron trapping effect of Ti 3 C 2 MXene and charge carrier separation for achieving superior PEC water splitting activity. • Transformation of multilayer Ti 3 C 2 MXene into monolayer • Swapping of Ti 3 C 2 MXene position on and under the ZnO • Monolayer Ti 3 C 2 MXene interface interaction with flake-like ZnO. • Improved charge carrier separation at the interface of ZnO/Ti 3 C 2 than Ti 3 C 2 /ZnO.