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Water-Dissociation-Assisted Electrolysis for Hydrogen Production in a Salinity Power Cell

Chen, Xia, Jiang, Chenxiao, Shehzad, Muhammad Aamir, Wang, Yaoming, Feng, Hongyan, Yang, Zhengjin, Xu, Tongwen
ACS sustainable chemistry & engineering 2019 v.7 no.15 pp. 13023-13030
ammonia, electric potential difference, electrodes, electrodialysis, electrolysis, feedstocks, fuels, hydrogen, hydrogen production, liquids, salinity, thermodynamics
Salinity gradient power (SGP) has attracted extensive research interests as a renewable energy source. Compared with energy generated from solar and wind, the direct adoption of SGP is currently impractical. Splitting water in salinity-gradient-power driven reverse electrodialysis appears to be an effective way to utilize such energy, producing high-purity H₂, which could then serve as fuel or essential feedstock. However, H₂ production on the electrode is passivated by the high water-splitting voltage and the electrode overpotentials. Here in this work, we report a novel water-dissociation-assisted hydrogen production in a salinity gradient power system, by introducing bipolar membrane as the key element. The results indicate that the thermodynamic water-splitting voltage was shifted from 1.23 to 0.4 V, producing H₂ at 5.6 L·h–¹·m–²-electrode with a hydrogen-conversion efficiency of up to 91 ± 6%. We envision that the produced H₂ can be exploited for ammonia and synthetic gas/liquid production, contributing to a net-zero emission energy system.