The reversible reduction protons to dihydrogen: 2H⁺ + 2e ⇌ H₂ is deceptively the simplest of reactions but one that requires multistep catalysis to proceed at practical rates. How the metal–sulfur clusters of the hydrogenases catalyse this interconversion is currently the subject of extensive structural, spectroscopic and mechanistic studies of the enzymes, of synthetic assemblies and of in silico models. This is driven both by curiosity and by the view that an understanding of the underlying chemistry may inform the design of new electrocatalytic systems for hydrogen production or uptake, pertinent to energy transduction technology in an ‘Hydrogen Economy’. Can chemists design materials that replace the expensive platinum metal catalysts of fuel cells with metal–sulfur cluster assemblies utilising abundant Ni, Fe and S as in the natural systems? Here we review the state of the art.

(1) Background: There is a growing need for the development of new methods for the synthesis of nanoparticles. The interest in such particles has raised concerns about the environmental safety of their production methods; (2) Objectives: The current methods of nanoparticle production are often expensive and employ chemicals that are potentially harmful to the environment, which calls for the development of “greener” protocols. Herein we describe the synthesis of gold nanoparticles (AuNPs) using plant extracts, which offers an alternative, efficient, inexpensive, and environmentally friendly method to produce well-defined geometries of nanoparticles; (3) Methods: The phytochemicals present in the aqueous leaf extract acted as an effective reducing agent. The generated AuNPs were characterized by Transmission electron microscopy (TEM), Scanning electron microscope (SEM), and Atomic Force microscopy (AFM), X-ray diffraction (XRD), UV-visible spectroscopy, energy dispersive X-ray (EDX), and thermogravimetric analyses (TGA); (4) Results and Conclusions: The prepared nanoparticles were found to be biocompatible and exhibited no antimicrobial or antifungal effect, deeming the particles safe for various applications in nanomedicine. TGA analysis revealed that biomolecules, which were present in the plant extract, capped the nanoparticles and acted as stabilizing agents.

The synthesis and characterisation of the first {2Fe2S}-cluster bearing both CO and CN ligands is described; the iron atoms are linked by the bridging 1,3-propanedithiolate unit that has been identified in the crystallographic structure of the {2Fe2S} sub-unit of the H-centre of the all-iron hydrogenase from Desulfovibrio desulfuricans.

Bionanoscience/technology sits at the interface of chemistry, biology, physics, materials science, engineering and medicine and involves the exploitation of biomaterials, devices or methodologies on the nanoscale. One sub-field of bionanoscience/technology is concerned with the exploitation of biomaterials in the fabrication of new nano-materials and/or -devices. In this Perspective we describe examples of how plant viruses, focusing particularly on cowpea mosaic virus, a naturally occurring pre-formed sphere-like nanoparticle, are being used as templates and/or building blocks in bionanoscience and indicate their potential for future application.