MXenes in photocatalytic NOx abatement: Current innovations, opportunities, and challenges

MXenes possess unique properties that can be harnessed to address challenges in designing efficient photocatalysts for NOx oxidation. The review examines the synthesis of MXenes and their favorable photocatalytic properties and compares the performance of MXene-based photocatalysts to other hybrids. In addition, the review discusses the challenges and controversies associated with NOx removal using MXene-based photocatalysts, along with recommendations and opportunities for researchers in the field. The modeling of NOx oxidation kinetics and mechanisms are reviewed, and critical issues regarding catalyst deactivation and regeneration are discussed. Further, we discuss the often overlooked issues related to calculating the widely used figure of merit (DeNO(x) index) and propose a new paradigm for ranking photocatalysts based on the DeNO(x) index and NO conversion. Much work remains to be conducted to fully exploit the enormous potential of MXenes in photocatalysis, and this review is expected to inspire further exploration and spur breakthroughs in NOx abatement.