Bharati Panigrahy

Design of highly efficient cost effective and self-supported electrocatalyst for the production of green hydrogen with reduced CAPEX and OPEX is significant for renewable and sustainable energy conversion to achieve future carbon neutral. Meanwhile, as we know that the overall water splitting is an uphill reaction requires 285.8 kJ of energy, corresponds to the HHV of hydrogen, state-of-the-art developments are necessary to greatly improve the efficiency by rationally designing non-precious metal-based robust bi-functional catalysts for promoting both the cathodic hydrogen evolution and anodic oxygen evolution reactions. 

Here, first time we report the hybrid nanocomposite of Iron and Nickel phosphides based electrocatalyst directly grown on metal foam as an integrated electrode by a simple facile one step phosphidation process giving rise to highly crystalline composite with predominantly exposed [121] facets of nickel phosphide and [211] facets of iron phosphide, which accounts for the high electrocatalytic activities. The performance of metal phosphide towards hydrogen and oxygen evolution was examined under application relevant conditions in an anion exchange membrane electrolyzer and Alkaline electrolyzer cell stack. The formulated electrocatalyst outperforms other precious and non-precious electrodes operated at similar operating conditions. Evaluation of the in-house developed electrocatalyst in the prototype in-house design electrolyzer stack is conducted, and the efficiency of the electrolyzers are better, with the electrocatalyst cost is significantly cheaper compare to the commercial one. 

We have observed 14% less energy consumption compares to the commercial electrodes. We have achieved the increased efficiency by limiting 27% heat loss compare to commercial minimum of 50% by controlling the activation loss. We have carried out the mass balance and achieved close to 100% Faradic efficiency by minimizing the ohmic loss. Mass loss is also controlled by tuning the electron modulation followed by work function. By using the in-house developed electrode materials and technologies, we have successfully demonstrated prototype 1 kW alkaline and anion exchange membrane (AEM) electrolyzer cell stack module. We have evaluated the prototype 1 to 10 kW alkaline and AEM electrolyzers for more than 6 months to analyze the stability study. We have successfully established the increase in overpotential is less than 0.021 V with a constant current density of 0.6-1.1 A/cm2. The stability test is carried out with a potential range from 1.8 to 2.4 Volt and current density range of 0.1 to 1 A/cm2. For each case it is stable for more than 2000 hours. The in-house designed stacked electrolyzer exhibited stable performances with a hydrogen production rate of few Nm3 per hour without any decay, pave the path towards large scale application with 35% reduction in CAPEX and OPEX cost.