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Photoelectrochemical (PEC) systems are inefficient, probably due to charge carrier mobility, recombination rate, and solar light absorption. Fabricating semiconductor-metal sulfide nanocomposites and nanostructured materials can improve the absorption of solar radiation, electron–hole separation, transport, and hydrogen (H2) and oxygen generation to resolve the world's energy dilemma. The vanadium-doped (V) layered graphitic carbon nitride (g-CN)/MoS2 (MS) nanocomposite was synthesized employing two-step solvent evaporation and thermal condensation. This multilayer V-doped g-CN/MS nanocomposite broke down methyl red dye in 60 min under sunlight. Due to visible light absorption, the V-doped g-CN-MS nanostructure degrades the dye by 97.84%. We found that at 3.0 wt % V-doped g-CN/MS coated on TiO2 nanorods. The catalyst nanocomposites displayed a high photocurrent density of 23.72 mA cm–2 and a H2 production rate of 4477 mol h–1 cm–2. Additionally, the microstructure, optical absorption behavior, and electrical conductivity were all shown to contribute to these impressive PEC characteristics. The V-modified g-CN/MS nanocomposite structures are effective and regulated PEC catalysts, and this study suggests ways to improve PEC water splitting and degradation. [ABSTRACT FROM AUTHOR]

Electrochemical energy conversion and storage technologies involving controlled catalysis provide a sustainable way to handle the intermittency of renewable energy sources, as well as to produce green chemicals/fuels in an ecofriendly manner. Core to such technology is the development of efficient electrocatalysts with high activity, selectivity, long-term stability, and low costs. Here, two-dimensional (2D) carbonaceous materials have emerged as promising contenders for advancing the chemistry in electrocatalysis. We review the emerging 2D carbonaceous materials for electrocatalysis, focusing primarily on the fine engineering of active structures through thermal condensation, where the design, fabrication, and mechanism investigations over different types of active moieties are summarized. Interestingly, all the recipes creating two-dimensionality on the carbon products also give specific electrocatalytic functionality, where the special mechanisms favoring 2D growth and their consequences on materials functionality are analyzed. Particularly, the structure-activity relationship between specific heteroatoms/defects and catalytic performance within 2D metal-free electrocatalysts is highlighted. Further, major challenges and opportunities for the practical implementation of 2D carbonaceous materials in electrocatalysis are summarized with the purpose to give future material design guidelines for attaining desirable catalytic structures.