Boosting the overall electrochemical water splitting performance of pentlandites through non-metallic heteroatom incorporation

We report on synthesis of the heterotrimetallic pentlandite-type material Fe3Co3Ni3S8 (FCNS) in presence of suitable phosphorus-(FCNSP) and nitrogen-(FCNSN) donors for the overall electrochemical water splitting. Throughout the experiments, a preferential incorporation of N into the FCNS-lattice is observed whereas the addition of phosphorus generally leads to metal-phosphate-FCNS composites. The obtained FCNSP, FCNSN, and FCNSNP facilitate the oxygen evolution reaction (OER) at 100 mAcm(-2) in 1.0M KOH with overpotentials of 479, 440, and 427 mV, respectively, outperforming the benchmark IrO2 (564 mV) and commercial Ni metal powder (>600 mV). Likewise, FCNSN and FCNSNP reveal an improved performance toward the hydrogen evolution reaction (HER) in 0.5M H2SO4, outperforming the pristine FCNS. All materials re-vealed high stability and morphological robustness during OER and HER. Notably, DFT calculation suggests that N and P doping boost the OER activity of the pristine FCNS, whereas N doping enhances the HER activity.

Automated summary

In this study, the synthesis of heterotrimetallic pentlandite-type material Fe3Co3Ni3S8 (FCNS) in the presence of suitable phosphorus and nitrogen donors for electrochemical water splitting was reported. The preferential incorporation of N into the FCNS lattice was observed, while the addition of phosphorus led to metal-phosphate-FCNS composites. The doped FCNS materials showed improved performance in oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) compared to the pristine FCNS.