In situ synthesis of molybdenum carbide/N-doped carbon hybrids as an efficient hydrogen-evolution electrocatalyst

Abstract

The development of non-precious metal based electrocatalysts for the hydrogen evolution reaction (HER) has received more and more attention over recent years owing to energy and environmental issues, and Mo based materials have been explored as a promising candidate. In this work, molybdenum carbide/N-doped carbon hybrids (Mo 2 C@NC) were synthesized facilely via one-step high-temperature pyrolysis by adjusting the mass ratio of urea and ammonium molybdate. The Mo 2 C@NC consisted of ultrasmall nanoparticles encapsulated by N-doped carbon, which had high specific surface area. They all exhibited efficient HER activity, and the Mo 2 C@NC with a mass ratio of 160 (Mo 2 C@NC-160) showed the best HER activity, with a low overpotential of 90 mV to reach 10 mA cm À2 and a small Tafel slope of 50 mV dec À1, which was one of the most active reported Mo 2 C-based electrocatalysts. The excellent HER activity of Mo 2 C@NC-160 was attributed to the following features: (1) the highly dispersed ultrasmall Mo 2 C nanoparticles, which exhibited high electrochemically active surface areas; (2) the synergistic effect of the N-doped carbon shell/matrix, which facilitated the electron transport.

One-Pot Synthesis of W2C/WS2 Hybrid Nanostructures for Improved Hydrogen Evolution Reactions and Supercapacitors

“…Figure 2 e shows the C 1s profile and explores the graphitic sp 2 carbon peak at 284.7 eV and W-C peak at 283.0 eV for W 2 C [ 6 ]. For the W 2 C/WS 2 hybrid, C 1s spectrum produced the C-C 1 (284.4 eV), C-C 2 (285.2 eV), W-C (282.9 eV), C-O (286.3 eV), and C=O (288.9 eV) peaks [ 29 , 41 , 42 ]. Figure 2 f deconvolution peaks reveal the S 2p couplets of S2p 1/2 and S2p 3/2 at 163.1 and 161.8 eV for WS 2 , whereas, they are at 163.6 and 162.3 eV for the W 2 C/WS 2 hybrid , respectively [ 43 , 44 ].…”

Supported Heterostructured MoC/Mo2C Nanoribbons and Nanoflowers as Highly Active Electrocatalysts for Hydrogen Evolution Reaction

“…Thus, it has been of both fundamental and technological significance to develop low-cost, high-performance electrocatalyst for hydrogen evolution reaction (HER). Molybdenum carbides (e.g., Mo 2 C and MoC) have been recognized as a viable candidate due to its low costs and Pt-like d-band electronic structure and HER activity. , However, in earlier studies, molybdenum carbides are mostly prepared in the powder form − and involve rather tedious preparation procedures, , use of expensive organic solvents, and high-temperature annealing, which greatly restrict their commercial utilization . Additionally, the use of a polymer binder to immobilize the catalyst onto a glassy carbon electrode inevitably generates impedance against electron and mass transport and limits the catalytic activity …”

A Nanostructured Mo2C‐rGO Heterostructure as a stable Anode with ultra‐high capacity for Lithium‐Ion Battery**

“…Similarly Mo 6 + 3d 5/2 shows the peak at binding energy 233.29 eV and Mo 6 + 3d 3/2 at 235.37 eV for MoO 3 , which is formed due to surface oxidation. [35] The C 1s spectrum as shown in the Figure 4c could be fitted in the CÀ C/C=C and C=O/O=CÀ O at 284.5 eV and 285.8 eV, respectively. Figure 4d shows the O 1s spectrum, comprising two separate peaks at binding energy 530.5 eV and 532.4 eV for MoÀ O and C=O/O=CÀ O bond, respectively.…”

“…Figure 4d shows the O 1s spectrum, comprising two separate peaks at binding energy 530.5 eV and 532.4 eV for MoÀ O and C=O/O=CÀ O bond, respectively. [35][36][37][38]…”