Recent progress of two-dimensional MXenes in photocatalytic applications: a review

The two-dimensional transition metal carbides, nitrides, and/or carbonitrides (MXenes) were first synthesized in 2011. In the last couple of years, MXenes have drawn intense interest in the field of catalysts, ion batteries, energy storage, and sensors due to the high chemical diversity and structural complexity of MXenes. In this review, the preparation method, structure, and electronic and optical properties of MXene are introduced in detail. More importantly, MXenes, as a cocatalyst, are widely applied to combine with various common photocatalysts such as metal oxide, metal sulfide, and g-C3N4 to improve the performance of photocatalytic H-2 evolution, CO2 conversion, photocatalytic degradation of pollutants, and nitrogen fixation. The large specific surface area, hydrophilicity, excellent electronic conductivity, and surface groups of MXenes play crucial roles in boosting the photocatalytic efficiency of the semiconductor catalysts. Lastly, challenges and invigorating outlooks of the photocatalytic applications of MXene materials are also discussed and concluded. (C) 2020 Elsevier Ltd. All rights reserved.