Abstract
The generation of clean and sustainable hydrogen fuel through water splitting demands efficient and robust earth-abundant catalysts for the hydrogen evolution reaction (HER). A new hybrid, which was fabricated by incorporating molybdenum carbide (MoxC) nanoparticles into a nitrogen-implanted three-dimensional carbon matrix (MoCN-3D), was developed as a highly active and durable nonprecious metal electrocatalyst for HER. The porous architecture of MoCN-3D can provide continuous mass transportation with a minimal diffusion resistance and thus produce effective electrocatalytic kinetics in both acidic and alkaline media. Experimental observations in combination with density functional theory calculations reveal that the effective coupling between molybdenum carbide nanoparticles and the carbon matrix, as well as N hybrid coordination, can modify the electronic Fermi level of the final hybrid, which synergistically reduces the proton adsorption and the reduction barrier during electrocatalytic HER. A three-dimensional, porous catalytic framework makes it easier to flow water past active sites that turn this molecule into hydrogen. The hunt for cheaper alternatives to platinum catalysts for water splitting led Jinhua Ye from Tianjin University in China and co-workers to investigate molybdenum carbide (Mo2C). These catalysts show significant hydrogen evolution when confined to nanoscale shapes. The researchers enhanced this behaviour by replacing imidazole-zinc units in a zeolite-type metal organic framework with molybdenum. Heating at high temperature turned the sieve-like template into a new composite containing ultrafine Mo2C nanoparticles and a three-dimensional matrix of graphitic carbon implanted with nitrogen atoms. The physical structure of this material improves mass transport of reagents to and from catalytic surface sites, while favorable interactions between Mo2C and the carbon matrix lower energy barriers needed to slice water apart. A new hybrid, fabricated by incorporating molybdenum carbide (Mo2C) nanoparticles into nitrogen-implanted three-dimensional carbon matrix (MoCN-3D), has been developed as a highly active and durable nonprecious metal electrocatalyst for HER. The porous architecture of the developed catalyst MoCN-3D can provide continuous mass transportation with a minimal diffusion resistance and thus produce effective electrocatalytic kinetics in both acidic and alkaline media.
Highlights
Growing concerns about global warming and the depletion of petroleum resources have stimulated a great deal of interest in the development of novel technologies for clean and sustainable energy.The electrocatalytic reduction of water to molecular hydrogen via hydrogen evolution reaction (HER; 2H++2e → H2) provides a promising solution to future energy supplies.[1,2,3] Platinum (Pt) remains the most efficient electrocatalyst for HER; the high cost and limited supply of Pt necessitate finding an alternative cheap and abundant catalyst for HER applications.[4]
The zinc component was reduced by carbon to generate evaporative Zn at such a high temperature, whereas the Mo component was reacted with carbon and produced nanosized molybdenum carbide particles
Lattice fringes can be clearly observed in the high-resolution Transmission electron microscopy (TEM) images, in which the lattice spacing of 2.4 Å is assigned to the (0 0 2) interplane spacing of the molybdenum carbide nanoparticles, and the 3.4 Å belongs to the (0 0 2) plane of graphene (Figure 1g), revealing that graphitic carbons were formed by catalytic graphitization of amorphous carbon on the deposited Mo component.[14,16]
Summary
Growing concerns about global warming and the depletion of petroleum resources have stimulated a great deal of interest in the development of novel technologies for clean and sustainable energy.The electrocatalytic reduction of water to molecular hydrogen via hydrogen evolution reaction (HER; 2H++2e → H2) provides a promising solution to future energy supplies.[1,2,3] Platinum (Pt) remains the most efficient electrocatalyst for HER; the high cost and limited supply of Pt necessitate finding an alternative cheap and abundant catalyst for HER applications.[4]. Active nonprecious metal hydrogen evolution electrocatalyst: ultrafine molybdenum carbide nanoparticles embedded into a 3D nitrogen-implanted carbon matrix
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