As an alternative energy storage platform and carbon-free fuel, hydrogen has emerged as a leading candidate to address the impending energy crisis. Towards this end, hydrogenases, which are enzymes that carry out the reversible interconversion between protons and hydrogen gas, are of great interest. However, native hydrogenases are poorly suited for large-scale application due to their limited stability. Using Nature as inspiration, we seek to engineer new functionality into robust metalloprotein scaffolds. By introducing non-native metal-binding sites and redesigning the primary and secondary coordination spheres, we are able to introduce novel catalytic activity into simple electron transfer proteins. Here, we will present recent results from protein film voltammetry demonstrating high electrocatalytic proton reduction activity at modest overpotentials. Interaction of the active site with molecular hydrogen reduces this overpotential without inhibiting catalysis, in stark contrast to the native hydrogenases. Quantitative analysis of the atypical catalytic signals observed will be presented in the context of relative elementary rates for this multi-electron, proton-coupled reaction. A comprehensive model of the catalytic voltammograms encompassing variations in temperature, scan rate, pH, and rotation rate provides direct insight into the molecular mechanism of catalysis.

Electrocatalytic hydrogen production performed by model protein scaffolds

249th National Meeting (2015)

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