Ni5P4-NiP2 nanosheet matrix enhances electron-transfer kinetics for hydrogen recovery in microbial electrolysis cells

• Published in: Applied energy Vol. 209; pp. 56 - 64
• Main Authors: Cai, Weiwei, Liu, Wenzong, Sun, Haishu, Li, Jiaqi, Yang, Liming, Liu, Meijun, Zhao, Shenlong, Wang, Aijie
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01-01-2018
• Subjects: Electron transfer; Hydrogen recovery; Microbial electrolysis cell; Nickel foam phosphide; Microbial electrolysis cell; Electron transfer; Hydrogen recovery; Nickel foam phosphide
• ISSN: 0306-2619; 1872-9118
• DOI: 10.1016/j.apenergy.2017.10.082

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•One-step synthesis of the Ni5P4-NiP2 owns highly catalytic performance.•Enhanced electron transfer was achieved by expanding active sites.•NF-P as cathode showed a high hydrogen recovery in neutral condition.•3D NF-P cathode stimulated the functional genes over-presentation.
Due to the crucial role of the cathodic catalyst in the electron-transfer rate and hydrogen recovery in bioelectrochemical systems, coupling nickel and earth-abundant transition metal phosphides with high catalysis efficiency and low cost could provide a promising alternative to Pt/C catalysts. Herein, we fabricated a three-dimensional (3D) biphasic Ni5P4-NiP2 nanosheet matrix to act as a cathodic tunnel for electron transfer for hydrogen coupled with a microbially catalyzed bioanode. Benefiting from the “ensemble effect” of P, the Tafel slope obtained from voltammetry reflected the improved catalytic performance (83.9 mV/dec vs. 113.6 mV/dec) and contributed to a higher hydrogen production rate of 9.78 ± 0.38 mL d−1 cm−2 that was 1.5 times faster than that of NF, which was even faster than that reported for commercial Pt/C. The impedance resistance obtained using electrochemical impedance spectroscopy (EIS) showed that the NF-P simultaneously exhibited <10% electron loss, corresponding to a 2.5-fold improvement over the ∼25% electron loss of NF. The long-term durability of the new material was verified through long-term operation with high performance in practice. It is proved that a good catalytic property of cathode was well maintained, even with microorganism attachment on NF-P cathode.