Ru-Yi Liu,Lei Ding,Guo-Duo Yang,Jia-Yu Zhang,Rui Jiao,Hai-Zhu Sun
Although graphitic carbon nitride (g-C3N4) is one of the most promising metal-free semiconductors in the field of photocatalytic hydrogen production, the preparation of efficient g-C3N4-based photocatalysts is still a challenge. Herein, the strategy of element doping and co-catalyst loading are employed to make an effective modification on g-C3N4. The Mo2C hollow nanospheres supported by porous B-C3N4 (B-doped g-C3N4) flakes, namely, B-C3N4/Mo2C photocatalysts are successfully constructed by the ultrasonic self-assembly-calcination approach. The unique Mo2C hollow nanospheres structures increases internal multiple visible light scattering, which facilitates light-harvesting, shortens the transport distance of carriers, and hence reduces the carriers recombination. Impressively, B-C3N4/Mo2C-35 exhibits excellent activity in photocatalytic hydrogen production, affording an H2 production rate up to 1696.4 µmol g−1 h−1, which is higher than B-C3N4/3 wt% Pt photocatalyst. Moreover, the apparent quantum efficiency of B-C3N4/Mo2C-35 at 420 nm is 2.12%. Mechanism studies suggest that this desired photocatalytic performance is attributed to a broader light absorption range, more reactive sites and faster carrier transfer rate than that of pure g-C3N4. This work develops a noble metal-free hollow nanosphere co-catalyst system and proposes new insight into the design of g-C3N4-based composite photocatalysts.
Yaping Wang,Yike Li,Jingli Zhao,Jianshe Wang,Zhongjun Li
Developing high activity and eco-friendly photocatalysts for water splitting is still a challenge in solar energy conversion . In this paper, B doped g-C 3 N 4 quantum dots (BCNQDs) were prepared via a facile molten salt method using melamine and boron oxide as precursors. By introducing BCNQDs onto the surface of g-C 3 N 4 , g-C 3 N 4 /BCNQDs heterojunction was constructed via hydrothermal treatment . The resulting g-C 3 N 4 /BCNQDs heterojunction exhibits enhanced hydrogen evolution performance for water splitting under visible light irradiation . The mechanism underlying the improved photocatalytic activity was explored and discussed based on the formation of heterojunction between g-C 3 N 4 and BCNQDs with well-matched band structure .
Zhiqi Guo,Yao Tian,Guangjin Dou,Ye Wang,Jiaping He,Hao Song
Photocatalytic pure water splitting to produce H2 with a two-electron process is an effective and more kinetically favorable method to obtain clean energy. Herein, a CoP decorated 2D/2D red phosphorus/B doped g-C3N4 (CoP/RP/BCN) type II heterojunction is synthesized to realize photocatalytic pure water splitting via a two-electron process. The optimal ternary CoP/RP/BCN photocatalyst displays a prominent H2 yield of 166.2 μmol h−1 g−1, which is 207.8-fold greater than that of g-C3N4. The deep insight into the photocatalytic mechanism of CoP/RP/BCN reveals that the improved photocatalytic efficiency is ascribed to the synergistic effect of extended light absorption, accelerated charge transfer, and increased active reaction sites due to the novel heterostructure RP/BCN and co-catalyst CoP loaded. The introduction of B facilitates the intrinsic charge excitation and increases the work function of the carbon nitride framework, promoting charge transfer and heterojunction formation. With a phosphorization reaction, RP nanosheets tightly combine with BCN to enhance the visible-light absorption and construct the 2D/2D type II heterojunction. The difference in the work function between RP and BCN leads to band bending in the interface of the heterojunction, which induces an opposite migration of electrons and holes to enhance electron–hole pair separation. Moreover, CoP reduces water adsorption energy and provides H2 generation sites, facilitating the final step of pure water splitting to produce H2. This work proposes a promising strategy to achieve highly effective photocatalytic pure water splitting without any sacrificial reagents.
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