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Carbon dots (CDs) present unique photoinduced charge transfer and reservoir properties, showing promising application potential in photocatalysis. The in situ preparation of CDs in a graphitic carbon nitride (g‐C3N4) matrix provides not only a new approach for electronic structure modulation and heterostructure construction but also an effective way to improve their photocatalytic performance. However, incorporating CDs into ultrathin g‐C3N4 remains a challenge. Moreover, simultaneously tuning their carrier transport in inter‐ and intralayers is difficult but significant for their application as efficient photocatalysts. Herein, an unprecedented Se‐chaperoned thermal polymerization method for the synthesis of zero‐dimensional CD‐implanted g‐C3N4 nanosheets (CCNS) is reported. The CCNS simultaneously facilitate carrier transport and suppress recombination because of the seamless bonding heterostructure of CDs within the in‐plane domains of the g‐C3N4 nanosheets. Accordingly, the photocatalytic rates of water splitting for H2 evolution and CO2 reduction are enhanced 3.1 and 4.1 times, respectively. In addition, the photocatalytic RhB degradation efficiency dramatically increases 18 times. This work presents a promising solution to solving the current worldwide energy shortage and environmental pollution issues. [ABSTRACT FROM AUTHOR]

[Display omitted] • 1T-phase MoS 2 nanoparticles were successfully in-situ grown on B-doped g-C 3 N 4 nanosheets. • 1T-MoS 2 /CNB2 shows excellent hydrogen production activity (5334 μmol g−1 h−1, λ > 420 nm). • The corresponding mechanism is proposed based on DFT calculations and TA studies. The high photogenerated carrier recombination rate and the low visible light utilization limit the development of graphitic carbon nitride (CN) in industrial photocatalytic H 2 generation. Herein, 1T-phase MoS 2 nanoparticles with high conductivity and more active sites are in-situ grown on B-doped carbon nitride (CNB) nanosheets through a one-step hydrothermal method. The doping of boron element effectively improves the harvesting visible light ability by tuning the energy gap, while the introduction of 1T-phase MoS 2 successfully increases the carrier transfer rate by suppressing charge trapping. An optimized H 2 production activity of 5334 μmol h−1 g−1 with the apparent quantum efficiency of 10.2% is achieved by 1T-MoS 2 /CNB sample, which is 167 times higher than that of pure CN. The mechanism is systematically illustrated by the combination of DFT calculations and transient absorption measurements. This work provides a new way for the construction of transition metal-derived co-catalysts in photocatalytic hydrogen energy storage. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Hydroxyl decorated 0D g-C 3 N 4 NPs were synthesized via a simple hydrothermal method. • The NPs possess narrowed bandgap, increased surface area and better hydrophily than bulk g-C 3 N 4. • ZnS-g-C 3 N 4 photocatalysts present a high photocatalytic activity of 112 μmol h−1. • Theoretical calculations are carried out to explain the high photocatalytic activity. • A systematic investigation of photocatalytic mechanism is proposed. Abstract Zero-dimensional graphitic carbon nitride nanoparticles (0D g-C 3 N 4 NPs) possess the advantages of non-toxicity, metal-free, and rich surface catalytic active sites. However, the complex preparation process, wide bandgap structure, easily particle aggregation and rapid carriers' recombination still limit their development in photocatalysis. Herein, these issues are addressed by synthesizing a novel hydroxyl (-OH) modified g-C 3 N 4 NPs with a simple hydrothermal method without using any etching agents. Besides the high hydrophily and small particle size, the OH decorated 0D g-C 3 N 4 NPs possess obvious narrowed bandgap and high reduction potential. To further improve their dispersity and carriers' separation rate, 0D/3D g-C 3 N 4 NPs/ZnS type II heterojunction is fabricated, which simultaneously improves the hydrophily, passivates the surface defects and extends the sunlight absorption range of ZnS. As a result, a high and cyclable photocatalytic activity of 112 μmol h−1 (5.6 mmol h−1 g−1) is achieved under visible light irradiation without any co-catalysts, which is 140 times higher than that of pure ZnS and much better than the pure 0D g-C 3 N 4 NPs. A systematic study of photocatalytic mechanism is proposed by combining the theoretical calculations and experimental results. This work offers a new sight for the design of 0D g-C 3 N 4 NPs based photocatalysts for H 2 production. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) ZnS-SnS 2 porous nanosheets are designed as clean and low cost photocatalysts for water splitting. The composites successfully combine high photoelectron reduction potential of ZnS with the sufficient sunlight harvesting ability of SnS 2 . Moreover, SnS 2 acts as an effective electron transfer medium from ZnS to SnS 2 due to the construction of quasi-type II structure. This greatly promotes the transfer of electron-hole pairs and effectively inhibits their recombination. Especially, the unique porous nanosheets structure maintains them high specific surface area and countless reactive sites, which increases the reactants' contact area and facilitates the migration of carriers upon photocatalysis. This further suppresses the charge recombination and improves the photocatalysts' stability. As a result, an optimized specific surface area of 246.7 m 2  g −1 and photocatalytic H 2 generation rate of 536 μmol h −1 g −1 are achieved in the absence of a surfactant and co-catalyst, which is 10 times higher than ZnS and 17 times higher than SnS 2 . In addition, the porous nanosheets have fairly good photocatalytic stability and can be reused at least five cycles without obvious changes in activity and structure. This work successfully presents the potential of ZnS and SnS 2 -based photocatalyst for clean and low cost hydrogen production from water splitting. [ABSTRACT FROM AUTHOR]