As an ideal fuel due to the advantages of no pollution, high combustion heat and abundant sources, hydrogen gas can be produced from organic matter through the electrohydrogenesis process in microbial electrolysis cells. But in many MECs, platinum is often used as catalyst, which limits the practical applications of MECs. To reduce the cost of the MECs, Ni-based alloy cathodes were developed by electrodepositing. In this paper hydrogen production using Ni-W-P cathode was studied for the first time in a single-chamber membrane-free MEC. At an applied voltage of 0.9 V, MECs with Ni-W-P cathodes obtained a hydrogen production rate of 1.09 m3/m3/day with an cathodic hydrogen recovery of 74%, a Coulombic efficiency of 56% and an electrical energy efficiency relative to electrical input of 139%, which was the best result of reports in this study. The Ni-W-P cathode demonstrated a better electrocatalytic activity than the Ni-Ce-P cathode and achieved a comparable performance to the Pt cathode in terms of hydrogen production rate, Coulombic efficiency, cathodic hydrogen recovery and electrical energy efficiency at 0.9 V.

Gas-liquid discharge coupling with photocatalysts is an effective approach to enhance the chemical activity of plasma treated liquid. However, the incomplete understanding of the discharge characteristics with the addition of photocatalysts remain. The characteristics of pulsed gas-liquid discharge (G-LD) combining TiO2 or WO3 are studied in this work to address this issue. Results indicate that the addition of photocatalysts significantly promote the discharge, as evidenced by the diagnosis of discharge current, optical emission spectra, concentrations of aqueous species and solution properties. Specifically, the addition of catalysts enhances the discharge current and enrich the emission spectrum. The atomic emission lines O (3p-3s), N (3p-3s) and Hα were also observed with the addition of TiO2, followed by higher content of reactive species in the solution. However, the destruction of discharge stability is also accelerated with the addition of catalysts. This study contributes to an improved understanding of the mechanism of gas-liquid discharge coupled with photocatalysts for the improvement in applications.

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