Global ammonia production reached 175 million metric tons in 2016, 90% of which is produced from high purity N2 and H2 gases at high temperatures and pressures via the Haber–Bosch process. Reliance on natural gas for H2 production results in large energy consumption and CO2 emissions. Concerns of human-induced climate change are spurring an international scientific effort to explore new approaches to ammonia production and reduce its carbon footprint. Electrocatalytic N2 reduction to ammonia is an attractive alternative that can potentially enable ammonia synthesis under milder conditions in small-scale, distributed, and on-site electrolysis cells powered by renewable electricity generated from solar or wind sources. This review provides a comprehensive account of theoretical and experimental studies on electrochemical nitrogen fixation with a focus on the low selectivity for reduction of N2 to ammonia versus protons to H2. A detailed introduction to ammonia detection methods and the execution of control experiments is given as they are crucial to the accurate reporting of experimental findings. The main part of this review focuses on theoretical and experimental progress that has been achieved under a range of conditions. Finally, comments on current challenges and potential opportunities in this field are provided.

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In this study CsH 2 PO 4 /polyvinylidene fluoride (PVDF) composite electrolytes were prepared by a slurry casting method and their application in intermediate temperature fuel cells (ITFCs) was investigated. The composite electrolytes consisted of a physical dispersion of CsH 2 PO 4 particles in the PVDF polymer network and were thin and flexible. The crystalline structure and thermal behavior of CsH 2 PO 4 were not influenced by the PVDF. The composite electrolyte with 70 wt% CsH 2 PO 4 showed a high conductivity of 10 mS cm −1 at 270 • C under 30% H 2 O/Ar atmosphere as well as a tensile strength of 7 MPa at room temperature. In addition, the composite electrolytes had area specific resistances of 0.99 and 0.72 cm 2 , for corresponding thicknesses of 101 and 67 μm, which are low values. The composite electrolyte with 70 wt% CsH 2 PO 4 showed stable conductivity at 259 • C under 30% H 2 O/Ar atmosphere for 48 h. A fuel cell assembled with this electrolyte exhibited an open circuit voltage of 0.92 V and a peak power density of 86 mW cm −2 , making the composite electrolyte a candidate electrolyte for ITFCs.

In this work, we report experimental studies on the disinfection of irrigation water using a flow cell assembled with low-cost graphite plates as both anode and cathode. Natural irrigation waters collected from two irrigation locations (Reservoir 225 and Bott Well Pond) in Hawaii were used, and synthetic irrigation waters were prepared based on the chemical analysis of natural irrigation waters. The concentration of chloride was 10.2 mg/L in the synthetic Reservoir 225 water and 6.9 mg/L in the synthetic Bott Well pond water. Escherichia coli K12 ER2738 was selected as a model bacterium to evaluate the disinfection capability of the flow cell. Experiments performed in the synthetic irrigation waters showed that E. coli was inactivated by free chlorine species electro-generated from oxidation of chloride ions at the graphite anode. Complete removal of E. coli was achieved within 10 min in the synthetic irrigation waters. The disinfection of the natural irrigation waters took about four times longer than the disinfection of the synthetic irrigation waters. This result is most likely due to the presence of organic matter (and possibly other oxidizable species) in the natural irrigation waters. © 2020 Water Environment Federation • Practitioner points • Electrochemical flow cell disinfects to 99.9% with commercial graphite electrodes. • E. coli is removed in 10 min from synthetic irrigation water by a flow cell. • E. coli removal takes 4× longer in natural irrigation water. • A minimum current density of ≥1 mA/cm 2 is required for disinfection. • The primary disinfection mechanism is through chlorine generated from chloride ions.

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