Kainan Song,Feng Xiao,Lijuan Zhang,Fan Yue,Xiaoyu Liang,Jide Wang,Xintai Su
A hybrid nanomaterial comprising of one-dimensional W 18 O 49 nanowires grown on two-dimensional g-C 3 N 4 sheets was prepared by a facile solvothermal process. Photocatalytic activity of these materials for H 2 generation under visible light was evaluated. The optimum efficiency of W 18 O 49 /g-C 3 N 4 composite photocatalyst at a mass content of 30% was up to 4.5 times as high as that of the pure g-C 3 N 4 . The significantly enhanced performance of W 18 O 49 /g-C 3 N 4 composites was mainly attributed to the synergistic effect between the interface of W 18 O 49 nanowires and g-C 3 N 4 sheets, involving stronger light absorption in the visible range, faster transfer and more efficient separation of the photo-generated electron-hole pairs. In short, the W 18 O 49 /g-C 3 N 4 hybrid nanomaterial was demonstrated to be an effective photocatalyst for H 2 production.
Modified g-C3N4 sheets (CNS) with a bandgap of 2.61 eV were fabricated through physical vapor deposition (PVD) of g-C3N4. During the PVD process, a series of gaseous derivatives derived from pristine g-C3N4 at 700 °C condense into CNS at low temperature (<400 °C). As a result, CNS still retains a typical semiconductor structure (bandgap of 2.61 eV), while at the same time, CN and O–H defect groups were introduced to its tri-s-triazine-based structure.
Ke Yang,Chan Li,Haoyuan Qi,Yunfei Dai,Yuhong Cui,Yibo He
The shuttle effect of polysulfides seriously hinders the practical application of lithium–sulfur (Li–S) batteries, and separator modification is supposed to be an effective way to solve this issue. Herein, MXene quantum dots (MQDs) were self-assembled on the surface of g-C3N4 sheets (g-C3N4@MQDs) by electrostatic adsorption principles to construct a functional layer on a Celgard separator. Making MXene into quantum dots was conducive to solving the agglomeration issue of its sheets, providing more active sites to capture the dissolved polysulfides. Moreover, the MQDs could also work as an electrocatalyst to further facilitate the Li2S catalytic conversion, obtaining a high deposition current and capacity (257.4 mA h g−1). Attributed to the regulation effect of MQDs toward the kinetic behavior of polysulfides, the shuttle effect was effectively mitigated. An as-fabricated Li–S battery with a heterostructured g-C3N4@MQD-based separator achieved a high specific capacity of 1433 mA h g−1 at 0.1 C, excellent rate performance (532 mA h g−1 at 4 C), and good cycling performance (0.024% capacity fading per cycle after 1000 cycles at 2 C). The rational design of the g-C3N4@MQD-based separator not only broadens the application of MQDs, but also presents new insights to develop high-performance Li–S batteries.
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