Chuhan Huang,Yu Ma,Qian Cheng,Xiaohan Liu,Hongman Sun,Fazle Subhan,Xinyuan Zhao,Youhe Wang,Zifeng Yan
The fundamental insights into the reaction mechanism, especially the electron transfer mechanism, are highly promising yet challenging for W 18 O 49 /g-C 3 N 4 heterojunction catalysts during photocatalytic nitrogen fixation. Herein, the 1D/2D nanostructured S-scheme heterojunctions were designed by in situ growth of 1D W 18 O 49 nanowires on 2D g-C 3 N 4 nanosheets through solvothermal method using methanol as solvent. In situ XPS analysis revealed that electrons in the conduction band of W 18 O 49 recombine with holes in the valence band of g-C 3 N 4 under the conduction effect of internal electric field, band bending, and Coulombic attraction in the W 18 O 49 /g-C 3 N 4 heterojunction. The photogenerated electrons are retained in g-C 3 N 4 , where the negative reduction potential of its conduction band enhances the activation of N 2 . As a result, the ammonia generation rate employing the optimal W 18 O 49 /g-C 3 N 4 heterojunction is 64.8 μmol g cat −1 h −1 , approximately double that of W 18 O 49 alone and 2.3 times higher than that of g-C 3 N 4 . The enhanced activity and facile methodology make the current material exceedingly appealing for implementation in photocatalytic nitrogen fixation for the synthesis of ammonia.
Yaocheng Deng,Chengyang Feng,Lin Tang,Yaoyu Zhou,Zhaoming Chen,Haopeng Feng,Jiajia Wang,Jiangfang Yu,Yani Liu
Multi-level and multi-angle designations of photocatalysts have attracted great attention to address the insufficient photogenerated charge generation and transformation in photocatalysis. In this study, we reported an ultrathin 1D/2D W 18 O 49 /g-C 3 N 4 nanocomposites with unique multiscale structure and electronic property through direct growth of 1D plasmonic W 18 O 49 nanowires onto the surface of 2D ultrathin g-C 3 N 4 nanosheets. Owing to the unique multiscale structure and electronic property, the synthesized nanocomposites present enhanced photocatalytic activity, owns the maximum removal efficiency of 96.3% and rate constant of 0.0464 min −1 for Ibuprofen (IBF) after 60 min under AM 1.5G light. Meanwhile, under near-infrared (NIR) light irradiation, the optimum UWN-3 present 39.2% removal efficiency of IBF and the reaction rate reached 0.0027 min −1 after 120 min. Additionally, the degradation pathway indicated that the decarboxylation process was the main decomposition route of IBF in this reaction system, and OH radical species attack process also contributed to the degradation of IBF. Scavenge experiments and mechanism analysis illustrated that IBF degradation in this reaction system mainly depends on h + , O 2 – and OH radical species, and the promoted photocatalytic performance of the synthesized ultrathin 1D/2D W 18 O 49 /g-C 3 N 4 nanocomposites are stem from the synergism of the multichannel photogenerated charge transfer pathways. The combination of the multichannel charge transfer pathways mentioned above resulted in the highly efficient photocatalytic activity of the ultrathin 1D/2D W 18 O 49 /g-C 3 N 4 nanocomposites.
Integrating g-C 3 N 4 with narrow-band semiconductor to construct a Z-scheme structured heterojunction has been regarded as a common strategy to improve the photocatalytic performance of g-C 3 N 4 . However, limited catalytic activity increment is achieved due to the contradiction of expanding the light absorption scope of traditional photo-oxidation semiconductors (PS II) and preserving their valance band oxidative abilities. Herein, to extend the light absorption range of g-C 3 N 4 based Z-scheme photocatalyst to the whole solar spectra while without losing the high oxidative ability of this system, we select the heavy doped W 18 O 49 as PS II and provide a facile in situ hydrothermal method to elaborately fabricate an rGO decorated W 18 O 49 @g-C 3 N 4 (r-CNW) Z-scheme photocatalyst. The prepared r-CNW-2 (with optimal W 18 O 49 to g-C 3 N 4 weight ratio of 1:2) exhibits improved photocatalytic performance with H 2 O 2 generation rates of 71, 58.5 and 6.3 μmol g −1 h −1 obtained under the simulated solar light, visible light (>400 nm) and NIR light (>800 nm) irradiation, respectively, which is 1.3 and 2 times higher than those of the g-C 3 N 4 counterparts (54, 29 μmol g −1 h −1 and even not detected).such outstanding performance of r-CNW-2 could be associated with the broader light absorption, fast charge separation, and rapid redox reactions. Moreover, the r-CNW-2 also displays an excellent E-coli inactivation activity, comparable to most g-C 3 N 4 -based photocatalysts. Our work gives a new insight through trading off light absorption and redox ability to fabricate efficient Z-scheme photocatalyst for photocatalytic H 2 O 2 generation and environmental remediation.
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