Synthesis of Co-Doped Tungsten Phosphide Nanoparticles Supported on Carbon Supports as High-Efficiency HER Catalysts

Abstract

Tungsten phosphide (WP) is believed to be a promising electrocatalyst in the electrochemical hydrogen evolution reaction (HER) for its unique catalytic performances. Nevertheless, its further application is severely limited by the agglomeration caused by the high preparation temperature (over 600 °C). Herein, we adopt a citric acid-guided two-stage aging method to prepare Co-doped WP with small particle size and higher dispersity on the surface of seven different carbon supports. Co is successfully incorporated into the lattice of WP, causing preferable catalytic performance. The introduction of seven different carbon supports enhances electronic metal-supported interaction and proves this two-stage aging method universal. The as-derived CoWP-CA/KB (two-step aging) featured a low overpotential of 111 mV to achieve a current density of 10 mA cm–2, along with a desirable Tafel slope of 58 mV dec–1, outperforming most of the WP-based electrocatalysts. Besides, the electrode possesses excellent stability for 60 h without significant attenuation. Its remarkable performance results from its structure (delicate particle size, uniform dispersion, and large specific surface area) and its electrocatalytic properties (large electrochemically active surface area, excellent electrical conductivity, enhanced interfacial charge transfer kinetics, and high turnover frequency). This novel synthesis strategy will be pivotal for designing robust non-noble metal-based electrocatalysts with high HER activity and durability to meet the future keen demand for hydrogen.

Unveiling the advantages of an ultrathin N-doped carbon shell on self-supported tungsten phosphide nanowire arrays for the hydrogen evolution reaction experimentally and theoretically

“…2d). 17,35 Thus, the existence of W δ+ and P δ− species indicates that WP was successfully fabricated in both WP@NC NA and WP NA catalysts. Besides, the C 1s spectrum of WP@NC NA (Fig.…”

“…The doublet appears at around 31.8 eV can be assigned to the W δ+ (0 < δ ≤ 3) cations in WP, 16,17,47 while the two doublets at around 32.3 and 36.2 eV are assigned to the oxidation states of W (W 4+ and W 5+ , respectively) induced by air exposure. 17,48 In the P 2p XPS spectrum, the doublet near 129.7 eV corresponds to P bonded to W in the form of metal phosphide (P δ− ), while the doublet between 133.8 and 134.4 eV is regarded as the oxidized P species (Fig. 2d).…”

“…To further elevate the HER performance of phosphides, numerous efforts have been devoted to adjusting the morphology, components, and size of these catalysts, as well as enhancing the conductivity. 15,[17][18][19][20][21] It should be noted that the surface oxidations of metal phosphides during storage and HER processes are serious issues, which have been demonstrated to be disadvantageous for the HER via screening the active sites and reducing the network conductivity of phosphides. 22,23 Packaging phosphides with carbon shells can not only enhance the durability of the phosphides, but also create more active sites for the HER derived from the unique interfacial interaction between the phosphides and carbon shells.…”

Ternary-phase nanostructure W3P/WP/W for high-performance pH-universal water/seawater electrolysis

“…Except for TPM-4, the high-temperature-induced overgrowth and agglomeration are not so severe due to the introduction of citric acid, as we reported before. 24 However, at an excessively high temperature (900 1C), the increase in particle size due to agglomeration and the decrease in crystallinity brought by the loss of non-metallic phase P are still inevitable. 28 Therefore, 850 1C is a moderate reduction temperature for forming the ternary mixed crystal, W 3 P/WP/W.…”

“…23 Meanwhile, we also adopted the citric acid aging method to weaken the disadvantages of particle agglomeration and overgrowth caused by high temperature, as we reported previously. 24 Herein, a unique ternary-crystal, W 3 P/WP/W, was successfully synthesized via the H 2 -TPR method. By comparing the relationship between different reduction temperatures and the ratio of each component in the final catalysts, we found the most desirable reduction temperature for the HER.…”