Efficient ternary CeFeCoP bifunctional electrocatalyst for overall water splitting

Abstract

Water electrolysis is a prospective technology that can be applied to hydrogen production. Currently, there are many catalysts for water splitting. Cerium (Ce) can be a catalyst itself and it also can be a catalyst promoter due to its flexible coordination and excellent redox ability. Here we try to introduce Ce into FeCoP catalyst, which has been proved to a promising electrocatalyst toward water splitting. The ternary CeFeCoP was prepared by hydrothermal on nickel foam (NF). Then low temperature phosphating is followed. The CeFeCoP/NF shows an efficient electrocatalytic performance. The CeFeCoP/NF electrocatalyst requires overpotential of 298 ​mV at current density of 50 ​mA ​cm−2 for oxygen evolution reaction (OER), much lower than 323 ​mV of FeCoP/NF; and it demands an ultralow overpotential of 97 ​mV to deliver a current density of 10 ​mA ​cm−2 for hydrogen evolution reaction (HER) with respect to 194 ​mV of FeCoP/NF. Moreover, it presents quite smaller Tafel slopes of 114 ​mV dec−1 (OER) and 147 ​mV dec−1 (HER) compared to 153 ​mV dec−1 (OER) and 159 ​mV dec−1 (HER) for FeCoP/NF. When CeFeCoP/NF is used as a bifunctional electrocatalyst for water splitting, a cell voltage of just 1.55 ​V can be achieved at 10 ​mA ​cm−2, which is much lower than 1.67 ​V of FeCoP/NF electrolyzer. Furthermore, the stability of CeFeCoP/NF electrolyzer can maintain 90% after 10 ​h of chronoamperometry test, displaying an excellent durability. This outstanding performance of CeFeCoP/NF can be attributed to larger electrochemical specific area, easier charge transfer process, and facilitated Ce3+↔ Ce4+ transformation of CeO2 after introducing Ce.