Binary molten salt in situ synthesis of sandwich‐structure hybrids of hollow β‐Mo₂C nanotubes and N‐doped carbon nanosheets for hydrogen evolution reaction

Abstract

Focused exploration of earth‐abundant and cost‐efficient non‐noble metal electrocatalysts with superior hydrogen evolution reaction (HER) performance is very important for large‐scale and efficient electrolysis of water. Herein, a sandwich composite structure (designed as MS‐Mo2C@NCNS) of β‐Mo2C hollow nanotubes (HNT) and N‐doped carbon nanosheets (NCNS) is designed and prepared using a binary NaCl–KCl molten salt (MS) strategy for HER. The temperature‐dominant Kirkendall formation mechanism is tentatively proposed for such a three‐dimensional hierarchical framework. Due to its attractive structure and componential synergism, MS‐Mo2C@NCNS exposes more effective active sites, confers robust structural stability, and shows significant electrocatalytic activity/stability in HER, with a current density of 10 mA cm−2 and an overpotential of only 98 mV in 1 M KOH. Density functional theory calculations point to the synergistic effect of Mo2C HNT and NCNS, leading to enhanced electronic transport and suitable adsorption free energies of H* (ΔGH*) on the surface of electroactive Mo2C. More significantly, the MS‐assisted synthetic methodology here provides an enormous perspective for the commercial development of highly active non‐noble metal electrocatalysts toward efficient hydrogen evolution.

Constructing interfacial polarization sites within a honeycomb-like porous structureviaa spatially confined-etching strategy for boosting electromagnetic wave absorption

“…34 The Mo 3d spectra (Fig. 3e) reveal three feature states: Mo 6+ (235.7 eV), Mo 4+ (232.5 eV), and Mo 2+ (228.8 eV), and Mo in the high-valence state may be caused by the surface oxidation of Mo 2 C. 35 However, the existence of the C–N bond and Mo–N bond in the sample indicates that strong interactions between electrons can promote electron transfer. As shown in Fig.…”

“…36 These analyses further indicate that Mo 2 C and C are successful combined and N element is successful doped, resulting in multiple heterointerfaces that can trigger multiple polarization relaxation to promote electromagnetic dissipation ability. 35…”

Salt-assisted synthesis of advanced carbon-based materials for energy-related applications

“…A low overpotential of only 98 mV was obtained to reach a current density of 10 mA cm −2 . 89 In recent years, a double carbon target (carbon neutrality and carbon peak) has become the aim of many countries, inspiring numerous scientists to engage in the conversion and utilization of CO 2 into value-added chemicals/materials. Excellent electrical conductivity is another feature of molten salts, which can expand their application scope.…”

The in situ phosphorization inducing oxygen vacancies in the core–shell structured NiFe oxides boosts the electrocatalytic activity for the oxygen evolution reaction

“…1 Hydrogen is recognized as an ideal energy carrier owing to its high energy density and zero carbon emission. 2 Among various hydrogen production methods, electrochemical water splitting is considered to be an environmental friendly and sustainable method to produce high-purity hydrogen. 3,4 Fundamentally, electrochemical water splitting consists of two half-reactions: the hydrogen evolution reaction (HER) on the cathode and oxygen evolution reaction (OER) on the anode.…”

“…6 Noble metal (Ir and Ru) based electrocatalysts show a good OER activity; however, the scarcity and high cost seriously restrict their wide application. 7,8 In recent years, researchers have revealed that transition metal-based oxides, 9–11 sulfides, 12,13 phosphides, 14,15 carbides 2,16,17 and alloys 18,19 also show promising catalytic properties for both the HER and OER, which are expected to replace precious metal oxide electrocatalysts.…”