Hydrogenase as the basis for green hydrogen production and utilization

Hydrogenase is a paradigm of highly efficient biocatalyst for H2 production and utilization evolved in nature. A dilemma is that despite the high activity and efficiency expected for hydrogenases as promising catalysts for the hydrogen economy, the poor oxygen tolerance and low yield of hydrogenases largely hinder their practical application. In these years, the enigmas surrounding hydrogenases regarding their structures, oxygen tolerance, mechanisms for catalysis, redox intermediates, and proton-coupled electron transfer schemes have been gradually elucidated; the schemes, which can well couple hydrogenases with other highly efficient (in)organic and biological catalysts to build novel reactors and drive valuable reactions, make it possible for hydrogenases to find their niches. To see how scientists put efforts to tackle this issue and design novel reactors in the fields where hydrogenases play crucial roles, in this review, recent advances were summarized, including different strategies for protecting enzyme molecules from oxygen, enzyme-based assembling systems for H2 evolution in the photoelectronic catalysis, enzymatic biofuel cells for H2 utilization and storage and the efficient electricity-hydrogen-carbohydrate cycle for high-purity hydrogen and biofuel automobiles. Limitations and future perspectives of hydrogenase-based applications in H2 production and utilization with great impact are discussed. In addition, this review also provides a new perspective on the use of biohydrogen in healthcare beyond energy.