A novel three-dimensional (3D) layered MoS 2 @graphene functionalized with nitrogen-doped graphene quantum dots (MoS 2 @N-GQDs-GR) composites as an enhanced electrochemical hydrogen evolution catalyst. The few layered MoS 2 nanoflowers supported on N-GQDs-GR surface were elaborately fabricated by one-pot hydrothermal method, which MoS 2 and N-GQDs-GR exist in a bonding manner of Mo-N. In addition, due to the layered MoS 2 sheet edge exposes more hydrogen evolution active sites and N-GQDs-GR have high conductivity, the composites exhibit prominent electrocatalytic activity with a low overpotential 99 mV, a small Tafel slope 49.3 mV/dec. Therefore, that the current work will develop HER catalysts may replace Pt.
Recently, ruthenium telluride (RuTe 2 ) has received widespread attention as an effective HER catalyst. In this work, ultrafine and well-dispersed RuTe 2 nanoparticles anchored on nitrogen and boron co-doped graphene (RuTe 2 /BNG) was developed by freeze-drying and facile pyrolysis method, demonstrating a brilliant HER performance. The overpotential of RuTe 2 /BNG at the current density of 10 mA cm −2 is only 34 and 16 mV in 0.5 M H 2 SO 4 and 1.0 M KOH solution, respectively. More importantly, the RuTe 2 /BNG can also maintain significantly robust HER stability during long-term chronopotentiometry measurements. The outstanding HER activity of RuTe 2 /BNG should be ascribed to its properties with abundant defects, large specific surface area, high electronic conductivity and short mass transfer path. Our work offers a new path to fabricate efficient HER catalysts by homogeneously anchoring RuTe 2 on B, N co-doped graphene.
Xiuling Fan,Xiaoyan Wang,Weiyong Yuan,Chang Ming Li
Highly active, durable, and low-cost hydrogen evolution reaction (HER) catalysts are critical for large-scale energy storage in the form of hydrogen through water splitting but their fabrication presents great challenges. Herein we report the synthesis of a novel 3D hierarchical nanoporous CoP nanoflowers/pristine graphene interconnected network structure via diethylenetriamine (DETA)-mediated self-assembly, in which DETA promoted the uniform dispersion of graphene and the nucleation of the CoP precursor on graphene, the seed aggregation facilitated the formation of nanoflowers and a 3D network, and the gas release during the low-temperature phosphidation produced nanopores inside the nanoflowers. This nanoarchitecture shows an onset potential of −0.014 V, an overpotential of 98.1 mV to achieve 10 mA cm−2, a Tafel slope of 40.9 mV dec−1, and an exchange current density of 0.119 mA cm−2. The onset overpotential, overpotential to achieve 10 mA cm−2, and Tafel slope are all among the lowest reported for non-noble metal hydrogen evolution reaction (HER) catalysts, and the exchange current density also compares favorably to those of most reported HER catalysts. In addition, the catalyst exhibits excellent durability with negligible loss in current density after 2000 cyclic voltammetry (CV) cycles (+0.01 to −0.17 V vs. the RHE, at a scan rate of 100 mV s−1) or 23.5 h of chronoamperometric measurement at an overpotential of 98.1 mV, and a high faradaic efficiency of close to 100%. This work not only creates a high-performance and inexpensive HER electrocatalyst by utilizing the great advantages of 3D hierarchically nanostructured networks, but also develops a facile and economical strategy for the self-assembly of hierarchical nanostructures and offers scientific insight into its mechanism.
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