Searching for low-cost non-Pt catalysts for oxygen reduction reaction (ORR) has been a key scientific issue in the development of fuel cells. In this work, the potential of utilizing the experimentally available two-dimensional (2D) Fe-phthalocyanine (Fe-Pc) monolayer with precisely-controlled distribution of Fe atoms as a catalyst of ORR was systematically explored by means of comprehensive density functional theory computations. The computations revealed that O2 molecules can be sufficiently activated on the surface of the Fe-Pc monolayer, and the subsequent ORR steps prefer to proceed on the Fe-Pc monolayer through a more efficient 4e pathway with a considerable limiting potential of 0.68 V. Especially, the Fe-Pc monolayer is more stable than the Fe-Pc molecule in acidic medium, and can present good catalytic performance for ORR on the addition of axial ligands. Therefore, the Fe-Pc monolayer is quite a promising single-atom-catalyst with high efficiency for ORR in fuel cells.

Background Microbial electrosynthesis (MES) is a biocathode-driven process, in which electroautotrophic microorganisms can directly uptake electrons or indirectly via H 2 from the cathode as energy sources and CO 2 as only carbon source to produce chemicals. Results This study demonstrates that a hydrogen evolution reaction (HER) catalyst can enhance MES performance. An active HER electrocatalyst molybdenum carbide (Mo 2 C)-modified electrode was constructed for MES. The volumetric acetate production rate of MES with 12 mg cm −2 Mo 2 C was 0.19 ± 0.02 g L −1 day −1 , which was 2.1 times higher than that of the control. The final acetate concentration reached 5.72 ± 0.6 g L −1 within 30 days, and coulombic efficiencies of 64 ± 0.7% were yielded. Furthermore, electrochemical study, scanning electron microscopy, and microbial community analyses suggested that Mo 2 C can accelerate the release of hydrogen, promote the formation of biofilms and regulate the mixed microbial flora. Conclusion Coupling a HER catalyst to a cathode of MES system is a promising strategy for improving MES efficiency. Electronic supplementary material The online version of this article (10.1186/s13068-019-1413-z) contains supplementary material, which is available to authorized users.

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BACKGROUND Microbial electrosynthesis (MES) is a biocathode‐driven process, producing high‐value chemicals, from CO2. However, the low efficiency of the biocathode hinders the MES process efficiency significantly. RESULTS A novel 3D graphene–nickel foam (G‐NF) cathode has been fabricated, by hydrothermal approach for the improvement of microbially‐catalyzed reduction at the MES cathode. An increase of 1.8 times in the volumetric acetate production rate was obtained, compared with the untreated nickel foam. In MES with G‐NF, a volumetric acetate production rate of 3.11 mmol L‐1 day‐1 has been achieved; 70% of the electrons consumed were recovered and the final acetate concentration reached 5.46 g L‐1 within 28 days. CONCLUSION The hierarchical porous G‐NF cathode improved bacterial colonization and the efficiency of mass, nutrients and protons transfer due to its 3D composition; the graphene coating considerably increased the effective surface area for microbial adhesion, as well as the electron transfer rate of biofilm in the MES. This study attempted to improve the efficiency of the biocathode, and provides a promising large electrode for large‐scale MES devices. © 2017 Society of Chemical Industry

pH-gated ion channels in cell membranes play important roles in the cell's physiological activities. Many artificial nanochannels have been fabricated to mimic the natural phenomenon of pH-gated ion transport. However, these nanochannels show pH sensitivity only within certain pH ranges. Wide-range pH sensitivity has not yet been achieved. Herein, for the first time, we provide a versatile strategy to increase the pH-sensitive range by using dual amphoteric nanochannels. In particular, amphoteric polymeric nanochannels with carboxyl groups derived from a block copolymer (BCP) precursor and nanochannels with hydroxyl groups made from anodic alumina oxide (AAO) were used. Due to a synergistic effect, the hybrid nanochannels exhibit nanofluidic diode properties with single rectification direction over a wide pH range. The novel strategy presented here is a scalable, low-cost, and robust alternative for the construction of large-area membranes for nanofluidic applications, such as the separation of biomolecules.