Designing a low-cost, high-performance oxygen reduction reaction (ORR) catalyst to replace the precious metal catalyst remains a huge challenge for microbial fuel cells (MFCs). Herein, a facile and rapid approach to fabricate highly active N-doped hierarchical porous carbon (NHPC) supported bimetal CuCo/NHPC composites with densely accessible active sites is developed by pyrolysis of Cu-doped ZIF-67 (CuCo-ZIF) precursor. In which, CuCo-ZIF precursor is synthesized through a one-pot hydrothermal method . Results showed that in addition to create additional Cu-N x sites and increase N content, the Cu doping induces a hierarchical porous structure CuCo/NHPC composite with pores centered around 2.4, 4.2 nm and 10–60 nm, which can significantly accelerate the mass/electron transfer and improve efficient utilization of the active sites. The resulting CuCo/NHPC composite provides abundant active sites, high content of pyridinic-N and graphitic-N, which significantly boosts ORR performances. The CuCo/NHPC-T with pyrolysis temperature of 800 °C achieves remarkable ORR activity with low charge transfer resistances, high half-wave potential. The MFC assembled with CuCo/NHPC-800 (774.2 mW·m −2 and 0.713 V) significantly outperforms MFC assembled with Co-NC-800 (541.9 mW·m −2 and 0.583 V) in terms of maximum power density and open-circuit voltage. Moreover, the output voltage of MFC assembled with CuCo/NHPC-800 exhibited no significant downward trend within 30 days, which was better than that of Pt/C catalyst. This work provides a feasible time-saving route to develop promising nitrogen-enriched mesoporous carbon bimetallic ORR catalysts.
Yanru Zhu,Zhen Zhang,Yunfei Zou,Jian Zhang,Zhe An,Xin Shu,Hongyan Song,Jing He
Catalytic conversion of biomass-derived 5-(hydroxymethyl)furfural (5-HMF) into carbon-increased hydrocarbons as drop-in energy-rich biofuels has received a great deal of concern for the development of sustainable chemical industry. Here, we demonstrate a one-pot conversion of 5-HMF into C 9 -alkanes on one single catalyst, acidic–basic layered double oxides (Mg(Al)(Zr)O) supported CuCo alloy. The well-defined multifunctional catalytic sites with harmonious combination carry out cascade catalysis, affording C 9 -alkanes (including 30% of more value-added branched-cycloalkanes) in 83% yield. The basic–acidic sites on Mg(Al)(Zr)O show high activity for aldol condensation of 5-HMF and acetone, producing 4-[5-(hydroxymethyl)-2-furanyl]-3-buten-2-one (HAc) in a yield of >99%. The engineered Co–Cu–Co linkages on supported CuCo perform efficient hydrodeoxygenation, affording C 9 -alkanes in a selectivity of 96% from HAc. C 9 -cycloalkanes are generated from the cyclization of the corresponding monohydric alcohol intermediates by the synergy of acidic and CuCo sites in the hydrodeoxygenation reaction.
Electrocatalytic conversion of widely distributed nitrate from industrial wastewater into value-added ammonia was proposed as an attractive and sustainable alternative to harvesting green ammonia. Herein, CuCo alloys were facilely synthesized for nitrate conversion, while nonthermal Ar-plasma was employed to enhance the adhesion strength between the electrocatalyst and substrate interface via regulating the surface hydrophobicity and roughness. Based on Ar-plasma treatment, a high ammonia yield rate (5129.29 μg cm–2 h–1) was achieved using Cu30Co70 electrocatalyst −0.47 V vs RHE, while nearly 100% of Faradaic efficiency was achieved using Cu50Co50 electrocatalyst at −0.27 V vs RHE (reversible hydrogen electrode). Validated by in situ spectroscopy and density functional theory calculations, the high activity of the CuCo alloy was derived from the regulation of Co to weaken the strong adsorption capacity of Cu and the shift of the d-band center to lower the energy barrier, while Ar-plasma modification promoted the formation of *NO to boost nitrate conversion.
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