No abstract

Iron phthalocyanine (FePc) is a promising non-precious catalyst for the oxygen reduction reaction (ORR). Unfortunately, FePc with plane-symmetric FeN 4 site usually exhibits an unsatisfactory ORR activity due to its poor O 2 adsorption and activation. Here, we report an axial Fe-O coordination induced electronic localization strategy to improve its O 2 adsorption, activation and thus the ORR performance. Theoretical calculations indicate that the Fe-O coordination evokes the electronic localization among the axial direction of O-FeN 4 sites to enhance O 2 adsorption and activation. To realize this speculation, FePc is coordinated with an oxidized carbon. Synchrotron X-ray absorption and Mössbauer spectra validate Fe-O coordination between FePc and carbon. The obtained catalyst exhibits fast kinetics for O 2 adsorption and activation with an ultralow Tafel slope of 27.5 mV dec −1 and a remarkable half-wave potential of 0.90 V. This work offers a new strategy to regulate catalytic sites for better performance.

High-rate lithium (Li) ion batteries that can be charged in minutes and store enough energy for a 350-mile driving range are highly desired for all-electric vehicles. A high charging rate usually leads to sacrifices in capacity and cycling stability. We report use of black phosphorus (BP) as the active anode for high-rate, high-capacity Li storage. The formation of covalent bonds with graphitic carbon restrains edge reconstruction in layered BP particles to ensure open edges for fast Li+ entry; the coating of the covalently bonded BP-graphite particles with electrolyte-swollen polyaniline yields a stable solid–electrolyte interphase and inhibits the continuous growth of poorly conducting Li fluorides and carbonates to ensure efficient Li+ transport. The resultant composite anode demonstrates an excellent combination of capacity, rate, and cycling endurance.

Designing efficient electrocatalysts for hydrogen evolution reaction is significant for renewable and sustainable energy conversion. Here, we report single-atom platinum decorated nanoporous Co 0 . 85 Se (Pt/np-Co 0 . 85 Se) as efficient electrocatalysts for hydrogen evolution. The achieved Pt/np-Co 0 . 85 Se shows high catalytic performance with a near-zero onset overpotential, a low Tafel slope of 35 mV dec −1 , and a high turnover frequency of 3.93 s −1 at −100 mV in neutral media, outperforming commercial Pt/C catalyst and other reported transition-metal-based compounds. Operando X-ray absorption spectroscopy studies combined with density functional theory calculations indicate that single-atom platinum in Pt/np-Co 0 . 85 Se not only can optimize surface states of Co 0 . 85 Se active centers under realistic working conditions, but also can significantly reduce energy barriers of water dissociation and improve adsorption/desorption behavior of hydrogen, which synergistically promote thermodynamics and kinetics. This work opens up further opportunities for local electronic structures tuning of electrocatalysts to effectively manipulate its catalytic properties by an atomic-level engineering strategy.

Among them, the nitrogen-coordinated transition-metal (TM) single-atoms (SAs) supported on carbon substrates have emerged as a new class of ORR electrocatalysts with enormous potentials. [3-5] These SA electrocatalysts (SAECs) anchor TM-SAs to the carbon substrates via TMnitrogen (TMN x) coordination bonds that also act as the ORR active sites. It has been commonly accepted that the ORR activity of such TMN x-coordinated SA sites can be promoted by optimizing the binding strengths of ORR intermediates (e.g., *O 2 , *OOH, *OH, *O) to the active site via the altering of their electronic structures. [6] Various approaches have been reported to alter the electronic structures of TMN x-coordinated SA sites by modulating N types and coordinating numbers, [7] partially replacing N with other nonmetal elements (e.g., O, S, and P), [8] or the chemical compositions of carbon substrates. [9] Recently, the hetero-SAs (h-SAs) involving two different TMs (e.g., Co/Zn, Fe/Co, Fe/ Zn) have been successfully anchored to the carbon substrates as ORR SAECs. [10] Such an approach takes the advantage of the coexistence of two different TM-SA sites, through the pairing The development of oxygen reduction reaction (ORR) electrocatalysts based on earth-abundant nonprecious materials is critically important for sustainable large-scale applications of fuel cells and metal-air batteries. Herein, a hetero-single-atom (h-SA) ORR electrocatalyst is presented, which has atomically dispersed Fe and Ni coanchored to a microsized nitrogen-doped graphitic carbon support with unique trimodal-porous structure configured by highly ordered macropores interconnected through mesopores. Extended X-ray absorption fine structure spectra confirm that Fe-and Ni-SAs are affixed to the carbon support via FeN 4 and NiN 4 coordination bonds. The resultant Fe/Ni h-SA electrocatalyst exhibits an outstanding ORR activity, outperforming SA electrocatalysts with only Fe-or Ni-SAs, and the benchmark Pt/C. The obtained experimental results indicate that the achieved outstanding ORR performance results from the synergetic enhancement induced by the coexisting FeN 4 and NiN 4 sites, and the superior mass-transfer capability promoted by the trimodal-porous-structured carbon support. The development of oxygen reduction reaction (ORR) electrocatalysts based on earth-abundant nonprecious materials to replace the scarce platinum-group-metal-based ones is critically important for sustainable large-scale commercial applications of fuel cells and metal-air batteries. [1] The extensive research efforts over the recent years have led to a variety of The ORCID identification number(s) for the author(s) of this article can be found under