Construction of Z-scheme heterostructure is of great significance for realizing efficient photocatalytic water splitting. However, the conscious modulation of Z-scheme charge transfer is still a great challenge. Herein, interfacial Mo-S bond and internal electric field modulated Z-scheme heterostructure composed by sulfur vacancies-rich ZnIn2S4 and MoSe2 was rationally fabricated for efficient photocatalytic hydrogen evolution. Systematic investigations reveal that Mo-S bond and internal electric field induce the Z-scheme charge transfer mechanism as confirmed by the surface photovoltage spectra, DMPO spin-trapping electron paramagnetic resonance spectra and density functional theory calculations. Under the intense synergy among the Mo-S bond, internal electric field and S-vacancies, the optimized photocatalyst exhibits high hydrogen evolution rate of 63.21 mmol∙g−1·h−1 with an apparent quantum yield of 76.48% at 420 nm monochromatic light, which is about 18.8-fold of the pristine ZIS. This work affords a useful inspiration on consciously modulating Z-scheme charge transfer by atomic-level interface control and internal electric field to signally promote the photocatalytic performance.

Luminescent carbon quantum dots (CQDs) represent a new form of nanocarbon materials which have gained widespread attention in recent years, especially in chemical sensor, bioimaging, nanomedicine, solar cells, light-emitting diode (LED), and electrocatalysis. CQDs can be prepared simply and inexpensively by multiple techniques, such as the arc-discharge method, microwave pyrolysis, hydrothermal method, and electrochemical synthesis. CQDs show excellent physical and chemical properties like high crystallization, good dispersibility, photoluminescence properties. In particular, the small size, superconductivity, and rapid electron transfer of CQDs endow the CQDs-based composite with improved electric conductivity and catalytic activity. Besides, CQDs have abundant functional groups on the surface which could facilitate the preparation of multi-component electrical active catalysts. The interactions inside these multi-component catalysts may further enhance the catalytic performance by promoting charge transfer which plays an important role in electrochemistry. Most recent researches on CQDs have focused on their fluorescence characteristics and photocatalytic properties. This review will summarize the primary advances of CQDs in the synthetic methods, excellent physical and electronic properties, and application in electrocatalysis, including oxygen reduction reaction (ORR), oxygen evolution reaction (OER), hydrogen evolution reduction (HER), and CO2 reduction reaction (CO2RR).

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1wileyonlinelibrary.com on crystalline and molecular engineering could turn the band gap of g-C 3 N 4 by element doping, [4] using different precursors, [5][6][7][8][9] introducing crystal defects or amorphous structure, [3,10,11] forming carbon vacancies, [12] fabricating heterojunction composites, [13][14][15] and so on. Structural regulation mainly focused on increasing specific surface area, [16][17][18][19][20][21] typically making mesoporous by templates with high specific surface area. [16,17,20,21] However, most of studies reported focused on g-C 3 N 4 in the powder form due to the contradiction between the highly open framework and the insufficient mechanical strength. Some recent progresses have been made to achieve 3D macroform g-C 3 N 4 based on robust substrate, [19] but major challenges remain to develop a substrate-free g-C 3 N 4 film with high photocatalytic activity. Photonic crystals (PCs) are materials with spatially periodic variation of the dielectric permittivity on the order of the wavelength of light. The propagation of light within a certain frequency range is forbidden in a certain crystal direction within a certain spectrum regime, namely photonic stopband. [22,23] Special properties of PCs, such as inhibition of spontaneous emission, [24][25][26] slow light, and amplified photon absorption/emission, [27][28][29][30] provide numerous possibilities for "photon management" applications. Thus introducing PC structure is a promising strategy for promoting photocatalytic activity of photocatalyst and the performance in optoelectronic devices. [27][28][29][30][31][32][33] Consequently, if g-C 3 N 4 is fabricated in a PC form, the spontaneous emission by the recombination of photogenerated carriers could be inhibited and the photocatalytic activity could benefit from the bicontinous network with increased visible light absorption via slow photon effects.Inspired by considerations above, herein we demonstrate a general solution approach to tackle the challenge via a freestanding colloidal crystal templating method (see Scheme 1). Freestanding, highly ordered, crack-free silica PCs are generated by evaporative-vertical deposition. Subsequently, the calcination of the precursor dicyandiamide (DCDA) followed by removal of silica PCs generates highly uniform macroscopic g-C 3 N 4 PC films. The resultant freestanding g-C 3 N 4 PCs possesses a 3D interconnected network with tunable photonic stop band, exhibiting significantly improved photocatalytic activity in photodegrading and water splitting under visible light. Freestanding Graphitic Carbon Nitride Photonic Crystals for Enhanced PhotocatalysisLu Sun, Meijia Yang, Jianfeng Huang, Dingshan Yu, Wei Hong,* and Xudong Chen* Graphitic carbon nitride (g-C 3 N 4 ) has attracted tremendous attention in photocatalysis due to its extraordinary features, such as good thermal and chemical stability, metal-free composition, and easy preparation. However, the photocatalytic performance of g-C 3 N 4 is still restricted by the limited surface area, inefficient v...

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Dr. Jian-Feng Huang obtained his Ph.D. degree from School of Chemistry, Sun Yat-sen University in 2017. He is currently an associate researcher in Prof. Jun-Min Liu's group. His research interests mainly focus on the design and application of semiconductor based functional materials for photocatalysis. Yang Lei obtained his M.S. degree at Qingdao University of Science and Technology in 2018. He is currently a Ph.D. student under the supervision of Prof. Jun-Min Liu at School of Materials Science and Engineering, Sun Yatsen University. His research interests focus on carbon nitride based materials for photocatalytic hydrogen production and CO 2 reduction. Teng Luo obtained his B.E. degree at Donghua University in 2019. He is currently a M.E. student under the supervision of Prof. Jun-Min Liu at School of Materials Science and Engineering, Sun Yat-sen University. His research interests focus on dye-sensitized water-splitting cells.