Comprehensive Insight into Cobalt Phosphide in Untreated Natural Seawater Splitting: From Theoretical Prediction to Prototype Model

A strategy has been proposed for designing stable and high-performance oxygen evolution reaction (OER) catalysts, specifically for neutral seawater splitting. A promising series of dopants (Fe, Ni, V, Rh, Mn, and Ti) was identified from 3d to 4d transition metals to achieve economic and selective OER via DFT. Fe was selected as a promising dopant through DFT screening, which greatly improved the performance of the CoxP catalyst. In untreated natural seawater (pH 7.8), the potential of Fe/CoxP reached as low as 1.866 V at 100 mA·cm–2 and operated stably for 100 h. The improved Fe/CoxP can achieve a Faraday efficiency of 64.68%. The presence of Fe enhanced the corrosion resistance of CoxP, enhanced the strength of the Co–P bond, and inhibited the affinity between Co and Cl. In alkaline seawater, the performance and stability of Fe/CoxP were significantly improved with a wide pH adaptability. This work provides valuable insights into the selectivity dynamics between chlorine evolution reaction (CER) and OER on the cobalt phosphide surface, enhancing the understanding of catalyst behavior in the NaCl environment.