Highly active iron-nitrogen-boron-carbon bifunctional electrocatalytic platform for hydrogen peroxide sensing and oxygen reduction.

An iron-nitrogen-boron-carbon (Fe-N-B-C) bifunctional electrocatalyst was prepared by means of a facile one-step hydrothermal reduction of graphene oxide using dimethylamine borane as doping agent. In addition, hemins were efficiently anchored during doping/reducing process on this modified graphene. The as-prepared Fe-N-B-C electro-catalyst showed enhanced response as regards its potential for reduction of H2O2 and O2. In view of its catalytic activity, this Fe-N-B-C material was tested for the determination of H2O2 with a chronoamperometry method, obtaining a detection limit as low as 0.055 µM, which is better than that of some Hemin-N-C materials. Regarding O2 reduction reaction, a study performed using a rotating disk electrode indicated that this material exhibits a positive onset potential (0.90V vs. RHE), high selectivity (4e- process), high limiting-current density (4.75 mA cm-2) and strong resistance against the crossover-effect from methanol in alkaline medium, making it to be the promising candidate as alternative for commercial Pt/C catalysts. These results could have commercial and environmental relevance and would deserve further complementary investigation.

Biomass-derived N,S co-doped 3D multichannel carbon supported Au@Pd@Pt catalysts for oxygen reduction.

A beancurd-derived mesoporous carbon (NSC) was prepared by an environmentally friendly procedure, and then it was investigated as Au@Pd@Pt core-shell catalysts support (Au@Pd@Pt-NSC) for oxygen reduction reaction (ORR). The Au@Pd@Pt-NSC (E1/2 = 0.91 V) has a marginally negative ORR half-wave potential compared with other materials, in particular Pt/C (E1/2 = 0.87 V) and Au@Pd@Pt-C (E1/2 = 0.81 V). The specific and mass activities of the Au@Pd@Pt-NSC were 5 and 13 times higher than the commercial a Pt/C catalyst. After 20000 cycles of rapid durability test, the Au@Pd@Pt-NSC sample showed a loss of just 4.9% compared with the initial ECSA area, which can be attributed to the favorable interaction between Au@Pd@Pt and NSC. These results can be considered of environmental relevance and high potential applicability.

Fundamental understanding of nitrogen in biomass electrocatalysts for oxygen reduction and zinc-air batteries.

Exploring high-efficiency catalysts for oxygen reduction reactions (ORRs) is essential for the development of large-scale applications of fuel cell and metal-air batteries technology. The as-prepared Fe-NC-800 via polymerization-pyrolysis strategy exhibited superior ORR activity with onset potential of 1.030 V vs. reversible hydrogen electrode (RHE) and half-wave potential of 0.908 V vs. RHE, which is higher than that of the Pt/C catalyst and most of other Fe-based catalysts. The different d-band center values can be attributed to the influence of different N-doped carbon, leading to the adjustment in the ORR activity. In addition, Fe-NC-800-based Zn-air battery showed better electrochemical performance with a high discharge specific capacity of 806 mA h g-1 and a high-power density of 220 mW cm-2 than that of the Pt/C-based battery. Therefore, the biomass Fe-NC-800 catalyst may become a promising substitute for Pt/C catalysts in energy storage and conversion devices.