Hydrogen gas production with Ni, Ni–Co and Ni–Co–P electrodeposits as potential cathode catalyst by microbial electrolysis cells

Abstract

The development of efficient and economical cathode, operating at ambient temperature and neutral pH is a crucial challenge for microbial electrolysis cell (MEC) to become commercialize hydrogen production technology. In the present work, eight different electrodes are prepared by the electroplating of Ni, Ni–Co and Ni–Co–P on two base metals i.e., Stainless Steel 316 and Copper separately to use as cathode in MEC. Electrodeposited cathode materials have been characterized by XRD, XPS, FESEM, EDX and linear voltammetry. The fabricated cathodes show higher corrosion stability with improved electro-catalytic performance for the hydrogen production in the MECs as compared to the bare cathodes (SS316 and Cu). Data obtained from linear voltammetry and MEC experiments show that developed cathode possess four times higher intrinsic catalytic activity in comparison to bare cathode. Electrodeposited cathodes are intensively examined in membrane-less MEC, operating under applied voltage of 0.6 V in batch mode at 30 ± 2 °C temperature, in neutral pH with acetate as substrate and activated sludge as inoculum. Ni–Co–P electrodeposit on Stainless Steel 316 cathode gives maximum hydrogen production rate of 4.2 ± 0.5 m3(H2)m−3d−1, columbic efficiencies 96.9 ± 2%, overall hydrogen recovery 90.3 ± 4%, overall energy efficiency 241.2 ± 5%, volumetric current density 310 ± 5 Am−3. The net energy recovery and COD removal are 4.25 kJ/gCOD and 61%, respectively. Prepared cathodes show stable performance for continuous 5 batch cycle operations in MEC.