Chunli Cui,Genrui Zhang,Yu Yang,Tingting Wu,Lei Wang
Constructing heterojunction has been proved to be an efficient strategy for enhancing the photocatalytic performance of g-C 3 N 4 by prohibiting charge recombination and providing surface active sites. Herein, a novel structure of ultra-thin carbon bridged MoC quantum dots/g-C 3 N 4 nanosheets was constructed for the first time to facilitate carrier transfer and accelerate surface reactions. In our designed composites, a surface-to-surface contact has been formed between conductive carbon layer and g-C 3 N 4 nanosheet via ultrasonic assembly process. Moreover, there exist strong interfaces between MoC QDs and carbon layer because of the in-situ conversion method. As to this unique structure, the ultra-thin carbon layer functions as charge separation and migration high ways while the MoC QDs perform as noble-metal-free co-catalysts consuming the surface electrons promptly. Significantly, an optimal 40 wt% MoC QDs-C/g-C 3 N 4 photocatalyst (MCCN) is synthesized with a hydrogen evolution rate of 2989 μmol h −1 g −1 , which is 69.6 and 1.7 times higher than that of pure g-C 3 N 4 and Pt/g-C 3 N 4 , respectively. Our work provides new insights on designing highly efficient heterojunction photocatalysts for water splitting.
The development of high-performance electrocatalysts that rival Pt catalysts is crucial for efficiently driving the hydrogen evolution reaction (HER) to produce H2. Herein, we engineer sophisticated interfacial modulation of the Ru catalysts by constructing B, N co-doped porous carbon confined ultra-small MoC quantum dots (MoC@BNC) as an advanced catalyst carrier and stimulator. Combined experimental and theoretical calculations prove enhanced electron interaction between the Ru catalysts and the MoC quantum dots. Additionally, the B, N co-doped carbon substrate further refines the electronic structure of MoC, reinforcing the modulation of Ru catalysts. The Ru/MoC@BNC catalyst embodies a boosted H2O dissociation ability with a lowered H bonding strength, which promises an outstanding HER performance with an overpotential of 14 mV at 10 mA cm−2 in an alkaline solvent. Furthermore, robust catalytic stability is achieved with almost zero deterioration after the cycling test. This result exemplifies the importance of interfacial manipulation of the Ru catalysts to promote HER catalytic performance.
Lithium–ion batteries using Li 2 S cathode are considered as an optimal alternative for current lithium–ion batteries since their high theoretical capacity (1166 mAh/g) and high energy density (2600 W h kg −1 ). However, low electronic/ionic conductivity, severe lithium polysulfides (LiPSs) shuttle, and sluggish electrochemical reaction kinetics are the three major challenges for the practical application of Li 2 S. Herein, we report a multifunctional host of MoC quantum dots embedded in N–doped 2D nanocarbon (MoC@2D–NNC) with high electronic/ionic conductivity, strong LiPSs capture ability and superior electrochemistry catalytic activation for Li 2 S electrode. Nano Li 2 S is successfully entered into the MoC@2D–NNC to form MoC@2D–NNC/Li 2 S composite via facile liquid–phase dissolution precipitation. The obtained MoC@2D–NNC/Li 2 S composite displays a high electronic conductivity of 0.1624 S cm −1 , high initial discharge capacity of 1059 mAh/g, and long–term cycling performance over 1000 cycles. This reported MoC@2D–NNC/Li 2 S composite exhibits promising applications in advanced Li–S batteries.
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