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Extensive research is being done to develop multifunctional advanced new materials for high performance photocatalytic applications in the field of energy production and environmental detoxification, MXenes have emerged as promising materials for enhancing photocatalytic performance owing to their excellent mechanical properties, appropriate Fermi levels, and adjustability of chemical composition. Numerous experimental and theoretical research works implied that the dimensions of MXenes have a significant impact on their performance. For photocatalysis to thrive in the future, we must understand the current state of the art for MXene in different dimensions. Using MXene co-catalysts in widely used in photocatalytic applications such as CO 2 reduction, hydrogen production and organic pollutant oxidation, this study focuses on the most recent developments in MXenes based materials, structural modifications, innovations in reaction and material engineering. It has been reported that using 5 mg of CdS–MoS 2 -MXene researchers were able to generate as high as 9679 μmol/g/h hydrogen under visible light. The MXenes based heterojunction photocatalyst Co 3 O 4 /MXene was utilized to degrade 95% bisphenol A micro-pollutant in just 7 min. Numerous novel materials, their preparations and performances have been discussed. Depending upon the nature of MXene-based materials, the synthesis techniques and photocatalytic mechanism of MXenes as co-catalyst are also summarized. Finally, some final thoughts and prospects for developing highly efficient MXene-based photocatalysts are provided which will indeed motivate researchers to design novel hybrid materials based on MXenes for sustainable solutions to energy and pollution issues. [Display omitted] • MXenes as new interesting class of photocatalysts. • Composites and heterojunctions with 0D, 1D, 2D, 3D MXenes. • Variable and tunable optical band gaps. • Suitable for energy production and pollution mitigation. [ABSTRACT FROM AUTHOR]

[Display omitted] • Novel Z-scheme Bi 7 O 9 I 3 /B 4 C heterojunction synthesized by hydrothermal route. • Antibiotic as sacrificial agent- H 2 evolution and antibiotic removal simultaneously. • Antibiotic degradation route and photocatalytic mechanism probed. • Waste to clean energy concept. The dual-function photocatalytic systems with a promising capability for hydrogen evolution and simultaneous pollutant degradation are surely a significant step towards waste-to-energy conversion goals. However, the performance of such photocatalysts is often limited by poor visible-light activity, charge separation and surface reverse reaction involving photogenerated electrons and radicals/intermediates. In this work, we report hydrothermal synthesis of novel Bi 7 O 9 I 3 /B 4 C (BIBC) heterojunction photocatalyst for advanced Norfloxacin antibiotic degradation with simultaneous hydrogen evolution under visible light. In particular, BIBC-30 heterojunction shows H 2 evolution rate of 812 μmol g−1h−1 with simultaneous 94.2% NFN removal which are much higher than bare B 4 C (∼6 times) and Bi 7 O 9 I 3 (∼4 times). Under oxic/aerobic conditions too, a high 456.3 μmol g−1h−1H 2 evolution with nearly complete norfloxacin degradation was achieved. The low band gap of Bi 7 O 9 I 3 and presence of metallic Bio extends the absorbance to NIR region and B 4 C enlarges the surface area of junction along with suppression of the back reaction. It was observed that BIBC heterojunction exhibits manifolds H 2 evolution rate with NFN as sacrificial agent (18.3% apparent quantum efficiency) is manifolds higher than pure water, methanol, triethanolamine and rhodamine B. An effective Z-scheme charge transfer facilitated by Bio is active in the intimately coupled heterojunction with suitably placed energy bands. This work shows that waste to energy conversion can be promisingly achieved by performing H 2 evolution and pollutant removal simultaneously. [ABSTRACT FROM AUTHOR]