Research Projects

The rationale of the present project on green H2 production by direct seawater electrolysis (DSE) is significant and multifaceted. The limited resources and supply of fresh water for commercial-level electrolysis led the PI to formulate the idea for seawater splitting. Unfortunately, unlike freshwater splitting, DSE faces challenges, including the presence of impurities and ions (Na, Ca, Cl, etc.) in seawater that interfere with the process and reduce efficiency. Two major challenges impede seawater electrolysis: (i) the chlorine evolution reaction (CER), a rapid two-electron side reaction, kinetically competes with the more desirable four-electron oxygen evolution reaction (OER), even though OER is thermodynamically favored (with a potential window of ~480 mV at high pH); and (ii) the high concentration of chloride ions leads to significant electrode corrosion, thereby diminishing catalytic performance and long-term stability. Additionally, CER produces harmful Cl₂ gas at the anode and is kinetically more favorable than OER, making it a parasitic process. The key challenge to increase the efficiency of DSE is to develop robust electrocatalysts to be used in commercial electrolyzers. The commercially used Raney nickel, Ni-Co-oxide, Ni-hydroxide, etc., in alkaline water electrolyzers (AWE) and anion exchange membrane (AEM) electrolyzers are cheap but produce overall low current density and power density, high cell voltage, and low conversion efficiency, ultimately increasing the production cost of H₂. On the other hand, commercial proton-exchange membrane (PEM) electrolyzers use expensive Pt, Ru, and Ir-based electrocatalysts. To overcome these challenges, DSE requires the development of advanced catalysts that are both chlorine-resistant and rich in OER-active sites. These catalysts are essential to promote efficient water splitting while suppressing chlorine evolution, paving the way for practical and eco-friendly H₂ production from seawater. As preliminary experiments, we have designed some protocols for the development of a few morphology-oriented novel high-entropy metal phosphides (HEMPs) suitable for DSE. We observed high current & power density, low cell voltage, and stability from these HEMPs under DSE studies. Based on these promising preliminary results, we proposed four broad objectives in this proposal, namely (1) Advanced synthesis and characterization of morphology-oriented HEMPs nanoparticle catalysts, (2) HER and (3) OER studies on seawater, and (4) overall DSE and scale-up H₂ production. HEMPs are characterized by their synergistic high electrical conductivity, exceptional physicochemical properties, and ability to replace noble metals in catalytic reactions. Their low cost and abundance make them a promising alternative to traditional, more expensive catalysts. We will do innovative synthesis of pristine and dianionic HEMPs (e.g., CuMnFeCoNiP, SrFeCoNiCuP, CaMnCoNiCuP, CrMgFeCoNiP, MgFeCoNiCuPS, (CaFeMoCu)NiPS, MnFeCoNiCuPB etc.) catalysts. The as-obtained nanomaterials will be characterized for their phase purity, crystal structure, topology, morphology, and formation mechanism. Electrocatalysts synthesized in objective 1 will be used for H₂ evolution reaction (HER) and OER (objectives 2-3), and their structural evolution during reactive conditions will be studied via experiments. This insight will be critical to design a second generation of catalysts with improved activity and stability. Thereafter, the overall seawater splitting reaction (our deliverable cell voltage ~1.35-1.50 V) will be carried out using the optimized pH-responsive HER and OER electrocatalyst in an electrolyzer unit (objective 4). A specialized design, informed by a detailed understanding of the active sites and their deactivation mechanisms, will minimize HEMP catalyst poisoning by Cl⁻ and suppress both the CER and phosphate precipitation. Scale-up production of catalysts as well as H₂ will be done too (objective 4).