Abstract
A robust and efficient non-precious metal catalyst for hydrogen evolution reaction is one of the key components for carbon dioxide-free hydrogen production. Here we report that a hierarchical nanoporous copper-titanium bimetallic electrocatalyst is able to produce hydrogen from water under a mild overpotential at more than twice the rate of state-of-the-art carbon-supported platinum catalyst. Although both copper and titanium are known to be poor hydrogen evolution catalysts, the combination of these two elements creates unique copper-copper-titanium hollow sites, which have a hydrogen-binding energy very similar to that of platinum, resulting in an exceptional hydrogen evolution activity. In addition, the hierarchical porosity of the nanoporous copper-titanium catalyst also contributes to its high hydrogen evolution activity, because it provides a large-surface area for electrocatalytic hydrogen evolution, and improves the mass transport properties. Moreover, the catalyst is self-supported, eliminating the overpotential associated with the catalyst/support interface.
Highlights
A robust and efficient non-precious metal catalyst for hydrogen evolution reaction is one of the key components for carbon dioxide-free hydrogen production
Using density functional theory (DFT) calculations, we have demonstrated that the Cu-Cu-Ti hollow site on a Cu-Ti bimetallic surface exhibits an optimal hydrogen-binding energy (HBE) for hydrogen evolution reaction (HER)
In a recent study conducted by Durst et al, it is reported that the Volmer step is the rate-limiting step for HER on Pt/C in alkaline conditions, leading to a Tafel slope of about 120 mV dec À 1
Summary
A robust and efficient non-precious metal catalyst for hydrogen evolution reaction is one of the key components for carbon dioxide-free hydrogen production. It is widely believed that room temperature electrochemical reduction of water to molecular hydrogen offers a significant promise for supplying CO2-free hydrogen, which can be used directly as a fuel or as reactant to convert CO2 and to upgrade petroleum and biomass feedstocks to value-added chemicals and fuels through hydrotreating processes[8,9,10] All these applications require largescale, commercial processes for water electrolysis, which in turn require breakthrough discoveries in at least two areas: (i) the availability of electricity derived from renewable energy sources, such as solar and wind, and (ii) the discovery of low-cost electrocatalysts to replace precious metals that are currently the state-of-the-art hydrogen evolution reaction (HER) catalysts. These predictions are experimentally verified on both bulk Cu-Ti alloys and highly porous catalysts
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