We report the design, synthesis, and evaluation of a new type of non-precious-metal catalyst made from network polymers. 2,6-Diaminopyridine was selected as a building-block monomer for the formation of a nitrogen-rich network polymer that forms self-supporting spherical backbone structures and contains a high density of metal-coordination sites. A Co-/Fe-coordinating pyrolyzed polymer exhibited a high specific oxygen reduction activity with onset and half-wave potentials of 0.87 and 0.76 V vs RHE, respectively, in neutral media. There was no crossover effect of organics on its activity. The power output of a microbial fuel cell equipped with this catalyst on its cathode was more than double the output with a commercial 20 wt % Pt/C catalyst.

We reported a novel protocol to efficiently synthesize molybdenum carbonitride (MoCN) nanomaterials with dense active sites and high surface area. The key step in this protocol is the preparation of the catalyst precursor, which was obtained by polymerizing diaminopyridine in the presence of hydrogen carbonate. The abundant amino groups in the poly diaminopyridine bound numerous Mo species via coordination bonds, resulting in the formation of dense Mo active sites. The addition of hydrogen carbonate to the synthesis mixture resulted in CO2 gas evolution as the local pH decreased during polymerization. The in situ evolved CO2 bubbles mechanically broke down the precursor into MoCN nanomaterials with a high surface area. The synthesized MoCN materials were demonstrated as an electrocatalyst for hydrogen evolution reaction (HER). It exhibited an HER onset potential of -0.05 V (vs RHE) and a high hydrogen production rate (at -0.14 V vs RHE, -10 mA cm(-2)) and is therefore one of the most efficient, low-cost HER catalysts reported to date.

The lithium-O2 battery is one of most promising energy storage and conversion devices due to its ultrahigh theoretical energy density and hence has broad application potential in electrical vehicles and stationary power systems. However, the present Li-O2 battery suffers from a series of challenges for its practical application, such as its low capacity and rate capability, poor round-trip efficiency and short cycle life. These challenges mainly arise from the sluggish and unsustainable discharge and charge reactions at lithium and oxygen electrodes, which determine the performance and durability of a battery. In this review, we first provide insights on the present understanding of the discharge/charge mechanism of such a battery and follow up with establishing a correlation between the specific materials/structures of the battery modules and their functionality/stability within the recent progress in electrodes, electrolytes and redox mediators. Considerable emphasis is paid to the importance of functional orientation design and the synthesis of materials/structures towards accelerating and sustaining the electrode reactions of Li-O2 batteries. Moreover, the future directions and perspectives of rationally constructed material and surface/interface structures, as well as their optimal combinations are proposed for enhancement of the electrode reaction rate and sustainability, and consequently for a better performance and durability of such batteries.

As a potential energy carrier, hydrogen has surged up the priority list as part of broader decarbonization efforts and strategies to build or acquire a clean energy economy. Driven by...

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Efficient electrocatalysts for both the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are critical components of various energy conversion devices such as regenerative fuel cells and metal–air batteries. Herein, we report bifunctional transition-metal-doped carbon/nitrogen (M/C/N) materials that simultaneously electrocatalyze the ORR and OER. The OER potential of the Fe/C/N catalyst at a current density of 10 mA cm–2 was 1.59 VRHE, and its ORR half-wave potential was 0.83 VRHE. Significantly, the Fe/C/N catalyst provided a potential gap of 0.76 V between the OER potential (at 10 mA cm–2) and the ORR half-wave potential; this is the highest activity reported to date for a non-precious-metal catalyst. Two types of active center, the transition metal and a nitrogen atom, are likely responsible for the oxygen bifunctional activity.

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A step forward for tungsten: Nitrogen-rich tungsten carbonitride (WCN) nanomaterials can act as stable and efficient hydrogen evolution electrocatalysts with a much higher activity than conventional WCN materials. The use of a polymerization process provides a unique synthetic route to H2 WO4 nanoparticles, which can then be used to synthesize the WCN-derived catalysts.