Effect of temperature and current density on polybenzimidazole zirconium phosphate hybrid membrane in copper chloride electrolysis for hydrogen production

Abstract

This paper presents an elevated temperature copper chloride electrolysis as a sustainable hydrogen production using a modified polybenzimidazole (PBI) based membrane. The main objective of this work was to characterize the performance of PBI Zirconium Phosphate (PBI/ZrP) hybrid membrane and evaluate its use as potential working membrane in the hydrogen production. Temperature and current density effects on hydrogen production were investigated in the range of 100 to 115 °C and 0.1 to 0.5 A/cm2, respectively. PBI based hybrid membrane was synthesized with zirconium oxide (ZrO2) followed by phosphoric acid (PA) doping. The membrane properties was characterized for proton conductivity, thermal stability, copper diffusivity and tensile strength. The results revealed that modification of the PBI into PBI/ZrP has significantly increased the proton conductivity by four fold, and selectivity by 30%. However, there was a slight reduction in tensile strength by 5 MPa may due to the realignment of PBI/ZrP molecule structures. Furthermore, a higher current density (0.5 A/cm2) produced almost 40% more hydrogen (5.04 cm3/min) compared to 0.1 A/cm2 (3.64 cm3/min) at 115 °C with electrolysis efficiency of 97%. PBI/ZrP exhibited superior proton conductivity, thermally stable with high tensile strength. The synergistic of the pristine PBI with ZrO2 and PA doping has produced a hybrid PBI/ZrP membrane that can be a promising effective polymer electrolyte and budget friendly compared to Nafion.