In Situ CO₂-Emission Assisted Synthesis of Molybdenum Carbonitride Nanomaterial as Hydrogen Evolution Electrocatalyst

Abstract

We reported a novel protocol to efficiently synthesize molybdenum carbonitride (MoCN) nanomaterials with dense active sites and high surface area. The key step in this protocol is the preparation of the catalyst precursor, which was obtained by polymerizing diaminopyridine in the presence of hydrogen carbonate. The abundant amino groups in the poly diaminopyridine bound numerous Mo species via coordination bonds, resulting in the formation of dense Mo active sites. The addition of hydrogen carbonate to the synthesis mixture resulted in CO2 gas evolution as the local pH decreased during polymerization. The in situ evolved CO2 bubbles mechanically broke down the precursor into MoCN nanomaterials with a high surface area. The synthesized MoCN materials were demonstrated as an electrocatalyst for hydrogen evolution reaction (HER). It exhibited an HER onset potential of -0.05 V (vs RHE) and a high hydrogen production rate (at -0.14 V vs RHE, -10 mA cm(-2)) and is therefore one of the most efficient, low-cost HER catalysts reported to date.

Mo2C nanoparticles embedded within bacterial cellulose-derived 3D N-doped carbon nanofiber networks for efficient hydrogen evolution

“…Additionally, the Mo 3d can be deconvoluted into six peaks assignable to Mo 2+ (228.9, 232.6 eV), Mo 4+ (230.0, 233.1 eV) and Mo 6+ (233.5, 236.1 eV) species. 17,33 Mo 2+ is assigned to Mo 2 C, and Mo 4+ (MoO 2 ) and Mo 6+ (MoO 3 ) originate from superficial oxidation of Mo 2 C owing to air contact, which is consistent with previous reports. 15,34 The microstructure of Mo 2 C@N-CNFs was characterized by scanning electron microscopy and TEM (Figures 2a and b).…”

Solvothermal access to rich nitrogen-doped molybdenum carbide nanowires as efficient electrocatalyst for hydrogen evolution reaction

“…For both of the two samples, the peaks of Mo 3d can be divided into six peaks, indicating that Mo exists in three different states. The peaks located at 228.9 and 231.9 eV are attributed to Mo 3d 5/2 and 3d 3/2 of Mo 2þ in Mo 2 C, respectively [35]. And other four peaks are assigned to Mo 4þ and Mo 6þ due to the partial oxidation on the surface of Mo 2 C [36].…”

Strong interfacial coupling of MoS2/g-C3N4 van de Waals solids for highly active water reduction

“…Therefore, it is highly desirable to develop an earth-abundant, low-cost and highly active catalyst for producing hydrogen from water reduction. Although a wide spectrum of candidates have been explored, including transition metal dichalcogenides [5,6], carbides [7,8], phosphides [9,10] and nitrides [11], their HER catalytic performance are still inferior to platinum. In addition to the exploration of new materials, the HER catalytic performance could be considerably improved by means of material engineering and structure innovation, including increasing the density of reactive sites and enhancing the activity of the active sites [5,12].…”