We have sought to improve the electrocatalytic performance of tungsten nitride through synthetic control over chemical composition and morphology. In particular, we have generated a thermodynamically unstable but catalytically promising nitrogen-rich phase of tungsten via a hydrothermal generation of a tungsten oxide intermediate and subsequent annealing in ammonia. The net product consisted of three-dimensional (3D) micron-scale flower-like motifs of W2N3; this architecture not only evinced high structural stability but also incorporated the favorable properties of constituent two-dimensional nanosheets. From a performance perspective, as-prepared 3D W2N3 demonstrated promising hydrogen evolution reaction (HER) activities, especially in an acidic environment with a measured overpotential value of -101 mV at a current density of 10 mA/cm2. To further enhance the electrocatalytic activity, small amounts of precious metal nanoparticles (such as Pt and Au), consisting of variable sizes, were uniformly deposited onto the underlying 3D W2N3 motifs using a facile direct deposition method; these composites were applied towards the CO2 reduction reaction (CO2RR). A highlight of this series of experiments was that Au/W2N3 composites were found to be a much more active HER (as opposed to either a CO2RR or a methanol oxidation reaction (MOR)) catalyst.
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Research Article
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Nano Research 2020, 13(5): 1434-1443
Published: 09 March 2020
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