The vast majority of power/energy generation in our global economy is based on the chemical element carbon, specifically fossil carbon (coal) and hydrocarbon (oil and gas) fuels. Such an economy is not sustainable in the medium- to long-term for two fundamental reasons; first, there exists only a finite amount of fossil fuel, and, second, the carbon dioxide released during the combustion of fossil fuels induces anthropogenic climate change with costly and potentially disastrous consequences. Current energy technologies cannot support both a reduction in carbon dioxide emissions and an ever-expanding global economy. It is now recognized that hydrogen may be one of the leading contenders as a potential solution for a sustainable alternative to fossil fuels, especially for transport and for heat and power generation and energy storage. However, any transition from a carbon-based (fossil fuel) energy system to a hydrogen-based economy involves significant scientific, technological and socio-economic barriers. Our aim is to illustrate the “hydrogen nexus” as a possible connection or link from today's carbon economy to a sustainable energy future centred on hydrogen.

Introducing hierarchical pore structure to microporous materials such as metal-organic frameworks (MOFs) can be beneficial for reactions where the rate of reaction is limited by low rates of diffusion or high pressure drop. This advantageous pore structure can be obtained by defect formation, mostly via post-synthetic acid etching, which has been studied extensively on water-stable MOFs. Here we show that a water-unstable HKUST-1 MOF can also be modified in a corresponding manner by using phosphoric acid as a size-selective etching agent and a mixture of dimethyl sulfoxide and methanol as a dilute solvent. Interestingly, we demonstrate that the etching process which is time- and acidity- dependent, can result in formation of defective HKUST-1 with extra interconnected hexagonal macropores without compromising on the bulk crystallinity. These findings suggest an intelligent scalable synthetic method for formation of hierarchical porosity in MOFs that are prone to hydrolysis, for improved molecular accessibility and diffusion for catalysis.

Atomic pair distribution functions (PDFs) obtained from high energy x-ray synchrotron radiation and x-ray absorption fine structure measurements were performed on 18 closely spaced compositions of chalcogenide glasses (${\mathrm{Ge}}_x{\mathrm{Se}}_{1-x}$ with $0.15\le x\le 0.40$), which span the range of the floppy to rigid phase transition in these glasses. Structural parameters such as PDF peak widths, Debye–Waller factors from extended x-ray absorption fine structure, and the first sharp diffraction peak in $S\left(Q\right)$ were extracted as a function of composition. These parameters smoothly evolve with composition, but there are no clear discontinuities or breaks in the slope associated with the appearance of the intermediate phase (IP). Therefore, these measurements do not confirm a structural origin for the IP.

Biological substances based on proteins, including vaccines, antibodies, and enzymes, typically degrade at room temperature over time due to denaturation, as proteins unfold with loss of secondary and tertiary structure. Their storage and distribution therefore relies on a “cold chain” of continuous refrigeration; this is costly and not always effective, as any break in the chain leads to rapid loss of effectiveness and potency. Efforts have been made to make vaccines thermally stable using treatments including freeze-drying (lyophilisation), biomineralisation, and encapsulation in sugar glass and organic polymers. Here for the first time we show that proteins can be enclosed in a deposited silica “cage”, rendering them stable against denaturing thermal treatment and long-term ambient-temperature storage, and subsequently released into solution with their structure and function intact. This “ensilication” method produces a storable solid protein-loaded material without the need for desiccation or freeze-drying. Ensilication offers the prospect of a solution to the “cold chain” problem for biological materials, in particular for vaccines.

It is shown that a crystalline metal–organic framework (HKUST-1) can be rapidly synthesized from a DMSO/MeOH solution with greatly reduced amounts of organic solvents using a supercritical CO₂ (scCO₂) solvent expansion technique. The precursor solution is stable for months under ambient conditions, and CO₂-driven MOF (metal–organic framework) crystallization is achieved under mild conditions (40 °C, 40–100 bar) with excellent reproducibility. As the degree of liquid-phase expansion drives MOF nucleation and growth, the crystallite size and overall yield can be tuned by adjusting the CO₂ pressure. Furthermore, scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HR-TEM), and gas sorption analyses showed that, in the presence of scCO₂, HKUST-1 crystallites with a hierarchical pore structure are generated through a postcrystallization etching process. These findings demonstrate that scCO₂ is a time- and material-efficient route to MOF synthesis with a high level of control over the crystallization process for accessing tailored material properties.