Carbon-supported M x P y (M = Ni, Co, W, Cr, and Mo) were prepared via pyrolysis using a very simple and scalable method utilizing nontoxic metal and phosphorus precursors. The electrochemical hydrogen evolution (HER), oxygen reduction (ORR), and oxygen evolution (OER) reactions and corrosion resistance under both acidic and alkaline conditions were examined for all these catalysts and compared to those for the benchmark catalysts Pt/C (HER/ORR) and IrO2 (OER). The highest activities were found in alkaline solutions for Co2P for HER and ORR and Ni2P for OER. Good activity was also found in acid for some of these reactions, although the catalysts suffered from susceptibility to corrosion. Co2P was further studied in an alkaline environment, as it shows high catalytic activity toward the oxygen reduction reaction (ORR) without significant hysteresis. The onset potential (at 0.5 mA cm–2) obtained was 0.8 V vs RHE, and a Tafel slope value of 38 mV dec–1 was found with a maximum kinetic mass activity of 2870 A gCo –1 at 0.7 V vs RHE. Utilizing high-resolution transmission electron microscopy, it is possible to observe high-surface-area needle-like single-crystal cobalt oxide structures on the surface of the Co2P particles at the beginning of the ORR. Hence the high rates of initial corrosion of the Co2P appear to be associated with the dissolution and precipitation of cobalt oxide on the particle surface. The as-synthesized Co2P/C also shows good performance in an 8-h stability test for the OER, carried out at 1.6 V vs RHE in alkaline conditions, with negligible drop in current density over time. Interestingly, in an acidic environment the catalyst is very active toward two-electron oxygen reduction, leading to H2O2 with high selectivity (85%). It is intriguing that the pH dependence of this catalyst toward the ORR is similar to that seen for gold.

Batteries that extend performance beyond the intrinsic limits of Li-ion batteries are among the most important developments required to continue the revolution promised by electrochemical devices. Of these next-generation batteries, lithium sulfur (Li–S) chemistry is among the most commercially mature, with cells offering a substantial increase in gravimetric energy density, reduced costs and improved safety prospects. However, there remain outstanding issues to advance the commercial prospects of the technology and benefit from the economies of scale felt by Li-ion cells, including improving both the rate performance and longevity of cells. To address these challenges, the Faraday Institution, the UK’s independent institute for electrochemical energy storage science and technology, launched the Lithium Sulfur Technology Accelerator (LiSTAR) programme in October 2019. This Roadmap, authored by researchers and partners of the LiSTAR programme, is intended to highlight the outstanding issues that must be addressed and provide an insight into the pathways towards solving them adopted by the LiSTAR consortium. In compiling this Roadmap we hope to aid the development of the wider Li–S research community, providing a guide for academia, industry, government and funding agencies in this important and rapidly developing research space.

A functionalised benzoquinone redox species is coupled to the hydrogen/proton reaction to achieve a respectable reversible redox fuel cell (RFC).

The effect of doping Cr on the electrocatalytic activity of Co2P supported on carbon black (Cr x Co2–x P/CB) for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in alkaline solution was investigated. A beneficial improvement in the performance of Co2P toward HER and OER was discovered. For the HER at −200 mV overpotential, the turnover frequency (TOF) increases almost 6-fold from 0.26 to 1.52 electron siteCo –1 s–1 when Co2P/CB has a small amount of Cr added to form Cr0.2Co1.8P/CB. Similarly, we estimate an increase from 0.205 to 0.585 electron siteCo –1 s–1 for the OER at 1.6 V for the same change in composition. With 10 atom % Cr doping, the Cr0.2Co1.8P/CB catalyst needed 226 mV overpotential to produce a cathodic current density of −100 A gCo –1 and 380 mV overpotential to produce an anodic current density of 100 A gCo –1. Based on both experimental results and theoretical calculations, the activity improvement results from optimization of the electronic properties of Co2P after Cr doping.

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