Unraveling thermodynamics and bifunctional catalytic activity of Ni-doped LiCoPO4 for efficient alkaline water splitting

Developing highly stable and active bifunctional catalysts for overall water splitting (OWS) is significantly demanded for various energy storage and conversion devices. A series of Ni-doped LiCoPO4 [LiNixCo1-xPO4 (x = 0, 0.05, 0.1, 0.2)] were prepared by non-aqueous sol-gel method. Compared to bare LiCoPO4 (LCP1), Ni doping officiates its catalytic activity due to the synergetic effect, which is found to be the key factor for overall enhanced catalytic activity. All the catalysts show high activity even at elevated temperatures, a crucial requirement for stable and efficient commercial electrolyzers. All catalysts exhibit good potential for OWS but LCP4 (20 % Ni-doped LiCoPO4) outshines with excellent catalytic potential by virtue of its good electrochemical and thermodynamic parameters in 1 M KOH. Key metrics for OER and HER include low Tafel slopes (184 mV.dec−1 and 202 mV.dec−1), moderate overpotentials (385 mV and −571 mV), and low activation energies (11.96 kJ mol−1 and 19.71 kJ mol−1), respectively.