Impact of various 2D MXene surface terminating groups in energy conversion

Transition metal nitrides and/or carbides (MXenes) are a class of two dimensional (2D) materials with remarkable mechanical strength, carrier mobility, and other desirable characteristics. It has been suggested that the characteristics of these materials can be manipulated by adjusting the proportions of surface terminators like –O, –OH, –F, -Br, –I, –S, -Se, -Te, and –NH2. The Gibbs free energy and work function (Φ) of the adsorbed intermediate, specifically H∗ (∣△GH∗∣), on MXene can be regulated by surface terminating groups (-O, –OH, –F, -Cl, and -Br). This characteristic enables the utilization of MXene in catalytic applications. This study provides a comprehensive overview of the current advancements made in the morphological design of 2D MXene materials. The focus of this review is mostly on the critical examination of the influence of termination groups on catalytic activity and the selectivity of products. Ti3C2Tx MXene engineering design is extensively examined, with particular emphasis on hierarchical structures, quantum dots, and monolayers. To comprehensively comprehend the fundamental catalytic structure of Ti3C2Tx MXenes and the impact of various termination groups on the energy conversion process, it is essential to begin with an extensive literature analysis. This review encompasses an examination of their catalytic capabilities as well as an exploration of the mechanisms underlying the fabrication of surface terminating groups. Subsequently, a comprehensive analysis is presented regarding the ramifications of reaction parameters, challenges, and synthesis procedures in the context of tailoring the morphology of various MXene materials while controlling the presence of specific functional groups. Last, the future prospects for 2D MXenes application as green materials in reaction engineering and energy conversion applications are discussed.