In this paper, we reported that g‐C3N4/MIL‐53(Fe) composites were successfully fabricated through a simple grinding method, and they were used as photocatalysts to generate H2 from water under simulated sunlight irradiation. The introduction of g‐C3N4 into MIL‐53(Fe) could efficiently improve the H2 evolution rate from splitting water, which was attributed to the charge spatial separation between g‐C3N4 and MIL‐53(Fe). Impressively, g‐C3N4/MIL‐53(Fe)‐0.5 composite displayed the highest H2 evolution rate (0.9054 mmol g−1 h−1), about 335 and 47 times higher than that of pristine MIL‐53(Fe) 0.0027 mmol g−1 h−1 and g‐C3N4 (0.0193 mmol g−1 h−1), respectively. Further investigation demonstrated that an intimate interfacial contact, more active sites and well‐matched energy level were responsible for the enhancement of photocatalytic H2 evolution over g‐C3N4/MIL‐53(Fe) composites. To the best of our knowledge, this is the first report about using g‐C3N4/MIL‐53(Fe) composite as photocatalyst for H2 evolution. Thus, this study might open an avenue to fabricate the novel photocatalysts with superior activity.
A semiconductor heterojunction composed of silver cyanamide (Ag2NCN) and graphitic carbon nitride (g-C3N4) exhibited excellent photocatalytic activity for hydrogen evolution under simulated sunlight irradiation.
Recently, graphitic carbon nitride (CN) has been widely investigated for solar energy conversion through water splitting, but its low photocatalytic activity needs to be further improved and optimized. Herein, S/K co‐doped CN photocatalysts have been fabricated by condensation of thiourea and dithiooxamide followed by post‐treatment in molten salt. As evidenced by XRD patterns and UV–vis DRS plots, the engineering crystalline and electronic structure of all as‐prepared samples have been explored through tailoring the mass ratio of thiourea and dithiooxamide as well as ratio of molten salt/the precursor. After optimization, the as‐prepared S/K co‐doped CN photocatalysts with needle‐like nanorods structure exhibit excellent hydrogen evolution rate of 1962.10 μmol−1 g−1 h−1. While its photocatalytic activity is lower than that of pure CN by molten salt treatment (K‐doped CN) (2066.40 μmol−1 g−1 h−1), which results from that the K content of S/K co‐doped CN photocatalyst is lower than that of K‐doped CN. Moreover, compared with K‐doped CN, S/K co‐doped CN photocatalyst possesses higher photocatalytic performance when irradiated by a light source (λ > 520 nm). This might be ascribed to the fact that the introduction of sulfur can expand light absorption region (λ > 520 nm), whereas K cannot improve light absorption of CN in this wavelength region. Furthermore, DFT calculation reveals that both S and K atoms can offer more electrons to band gap, leading to the formation of metallic‐character band structure. In addition, K atom can intercalate in the interlayer of CN and bridge the adjacent two layers, leading to the formation of charge delivery channels. These results demonstrate that S/K co‐doped CN photocatalysts facilitate the separation and transport of photogenerated charge carries, resulting in the efficient photocatalytic activity for hydrogen evolution. Besides, a competition between sulfur and potassium atom during the synthesis process is also discussed in details.
In this paper, NiO/g‐C3N4 (NiO/CN) composites were successfully prepared by the wetness impregnation method using nickel ammine complex solution as NiO source. As photocatalysts, NiO/CN composites showed enhanced visible‐light photocatalytic hydrogen evolution activities in the presence of triethanolamine as sacrificial agent. The effects of NiO content and annealing temperature for NiO/CN composites on the photocatalytic H2 evolution activities were investigated. Furthermore, NiO/CN composite with 10.0% NiO content after annealing at 450 °C exhibited optimal photocatalytic H2 evolution rate of 90.05 μmol⋅h−1⋅g−1 which is about 17 times higher than that of pristine CN (5.22 μmol⋅h−1⋅g−1). Moreover, the experimental results demonstrated that amorphous NiO as co‐catalyst not only offered active sites for H2 evolution but also benefited the efficient separation of the photogenerated charge carries. In addition, NiO/CN composite displayed the superior photocatalytic stability during the photocatalytic process.
It remains a major challenge that the rational design high-efficiency electrocatalysts are applied to water oxidation in alkaline media. In this paper, Ni3+-rich nanograss-like Mo-doped Ni3S2/NiS/VS arrays grown on a...
Making several components be more intimate interfacial contacts in the photocatalyst is an efficient strategy to improve the separation and transfer of photogenerated charge carries and enhance the photocatalytic performance in the visible light region. In this work, a promising photocatalyst was fabricated by loading of Au nanoparticles and Cd(0.58)Zn(0.42)S nanoparticles onto the three dimensionally ordered mesoporous g‐C3N4 material (Au/3DOM CN/Cd(0.58)Zn(0.42)S) via two‐step synthesis method to significantly intensify the transfer capability of charge. The results of characterization demonstrate that Au/3DOM CN/Cd(0.58)Zn(0.42)S photocatalyst possesses the intimate interfacial contacts of three components and homogeneous wall thickness of 3DOM g‐C3N4 framework, and these properties give Au/3DOM CN/Cd(0.58)Zn(0.42)S photocatalyst an ability that it can harvest a wider range of visible light and endow it superior photocatalytic activities for hydrogen evolution from water splitting and RhB degradation. Finally, a possible mechanism was proposed based on the photoelectrochemical measurement. This work would provide a new strategy to design and fabricate g‐C3N4‐based with 3DOM architecture materials with superior photocatalytic activity.
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