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

Due to the crucial role of the cathodic catalyst in the electron-transfer rate and hydrogen recovery in bioelectro chemical 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 similar to 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.