We develop a host-guest strategy to construct an electrocatalyst with Fe-Co dual sites embedded on N-doped porous carbon and demonstrate its activity for oxygen reduction reaction in acidic electrolyte. Our catalyst exhibits superior oxygen reduction reaction performance, with comparable onset potential (E, 1.06 vs 1.03 V) and half-wave potential (E, 0.863 vs 0.858 V) than commercial Pt/C. The fuel cell test reveals (Fe,Co)/N-C outperforms most reported Pt-free catalysts in H/O and H/air. In addition, this cathode catalyst with dual metal sites is stable in a long-term operation with 50 000 cycles for electrode measurement and 100 h for H/air single cell operation. Density functional theory calculations reveal the dual sites is favored for activation of O-O, crucial for four-electron oxygen reduction.

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Here we report a precise control of isolated single ruthenium site supported on nitrogen-doped porous carbon (Ru SAs/N-C) through a coordination-assisted strategy. This synthesis is based on the utilization of strong coordination between Ru and the free amine groups (-NH) at the skeleton of a metal-organic framework, which plays a critical role to access the atomically isolated dispersion of Ru sites. Without the assistance of the amino groups, the Ru precursor is prone to aggregation during the pyrolysis process, resulting in the formation of Ru clusters. The atomic dispersion of Ru on N-doped carbon can be verified by the spherical aberration correction electron microscopy and X-ray absorption fine structure measurements. Most importantly, this single Ru sites with single-mind N coordination can serve as a semihomogeneous catalyst to catalyze effectively chemoselective hydrogenation of functionalized quinolones.

Platinum (Pt)-based catalysts have been unanimously considered the most efficient catalysts for the oxygen reduction reaction (ORR) in proton-exchange membrane fuel cells (PEMFCs). Unfortunately, the exorbitant cost of Pt hampers the widespread adoption and development of PEMFCs. Scientists have devoted tremendous efforts to achieving higher catalytic activity with less Pt usage by constructing delicate nanostructures. Substituting Pt with cheaper metals may be a feasible solution but suffers from a relatively low intrinsic activity. Recently, single-atom catalysts (SACs), which possess the highest metal utilization and excellent activity because of the minimum size of metal and unique coordination structure, are developing rapidly and have been regarded as a potential alternative to Pt-based materials. Here, we review the development of conventional Ptand nonprecious-metal-based ORR catalysts and summarize recent achievement in SACs for the ORR. A brief perspective on the remaining challenges and future directions of SACs is also presented.

Herein, we construct a novel electrocatalyst with Fe–Co dual sites embedded in N-doped carbon nanotubes ((Fe,Co)/CNT), which exhibits inimitable advantages towards the oxygen reduction reaction.

The formation of organic films on gold employing N-heterocyclic carbenes (NHCs) has been previously shown to be a useful strategy for generating stable organic films. However, NHCs or NHC precursors typically require inert atmosphere and harsh conditions for their generation and use. Herein we describe the use of benzimidazolium hydrogen carbonates as bench stable solid precursors for the preparation of NHC films in solution or by vapour-phase deposition from the solid state. The ability to prepare these films by vapour-phase deposition permitted the analysis of the films by a variety of surface science techniques, resulting in the first measurement of NHC desorption energy (158±10 kJ mol−1) and confirmation that the NHC sits upright on the surface. The use of these films in surface plasmon resonance-type biosensing is described, where they provide specific advantages versus traditional thiol-based films.

Photocatalysts based on g-C 3 N 4 by loading cocatalysts or constructing heterojunctions have shown great potential in solar-driven water oxidation. However, the intrinsic drawbacks of g-C 3 N 4 , such as poor mass diffusion and charge separation efficiency, remain as the bottleneck to achieve highly efficient water oxidation. Here we report a simple protonation method to improve the activity of g-C 3 N 4 . Studies using valence band X-ray photoelectron spectra and steady-state and time-resolved spectroscopy reveal that the promotion of catalytic ability originates from the higher thermodynamical driving force and longer-lived charge separation state, which may provide guidance in designing efficient polymeric semiconductor photocatalysts with desirable kinetics for water oxidation.