Transition metal carbides and nitrides (MXenes), as a promising class of two-dimensional inorganic compounds, are materials composed of a few atomic layers of transition metal carbides, nitrides, or carbonitrides. The properties of an MXene can be ingeniously regulated according to the external strain and the number of layers in the crystals and thin films. Single- and few-layered MXenes (SFL-MXenes) show preferable properties, such as a low ion diffusion barrier, low open-circuit voltage, and high specific surface area. In this review, we comprehensively summarize current advances in SFL-MXene research. The fabrication of SFL-MXenes via both top-down and bottom-up strategies is summarized in detail. Top-down strategies involve HF etching, in situ HF etching, molten salt etching, and electrochemical etching methods. Bottom-up strategies involve chemical vapor deposition, self-assembly, and template-assisted growth approaches. Additionally, applications of SFL-MXenes, including energy storage, energy conversion, sensing, optoelectronic, optical device, electromagnetic, and environmental applications, are illustrated. Finally, future challenges faced by SFL-MXenes and their application potential are summarized. With increasing progress in fabrication approaches using controlled synthesis, the unusual properties of SFL-MXenes can be unveiled and exploited for various prospective applications.

Solar light is an inexpensive energy source making up for energy shortage and solving serious environmental problems. For efficient utilization of solar energy, photocatalytic materials have attracted extensive attention over the last decades. As zero-dimensional carbon nanomaterials, fullerenes (C₆₀, C₇₀, etc.) have been extensively investigated for photocatalytic applications. Due to their unique properties, fullerenes can be used with other semiconductors as photocatalyst enhancers, and also as novel photocatalysts after being dispersed on non-semiconductors. This review summarizes fullerene-based materials (including fullerene/semiconductors and fullerene/non-semiconductors) for photocatalytic applications, such as water splitting, Cr (VI) reduction, pollutant degradation and bacterial disinfection. Firstly, the optical and electronic properties of fullerene are presented. Then, recent advances in the synthesis and photocatalytic mechanisms of fullerene-based photocatalysts are summarized. Furthermore, the effective performances of fullerene-based photocatalysts are discussed, mainly concerning photocatalytic H₂ generation and pollutant removal. Finally, the current challenges and prospects of fullerene-based photocatalysts are proposed. It is expected that this review could bring a better understanding of fullerene-based photocatalysts for water treatment and environmental protection.