Urchin-like bifunctional CoP/FeP electrocatalyst for overall water splitting

• Published in: International journal of hydrogen energy 2024-12, Vol.93, p.147-157
• Main Authors: Guan, Mengyuan, Fu, Shaobo, Qin, Fangfang, Zuo, Pingping, Shen, Wenzhong
• Format: Article
• Language: English
• Subjects: Cobalt phosphide; Electronic structure; Iron phosphide; Overall water splitting
• ISSN: 0360-3199
• DOI: 10.1016/j.ijhydene.2024.10.356

Developing efficient bifunctional electrocatalysts is crucial for advancing the practical application of electrocatalytic water splitting. Cobalt phosphide (CoP) shows great potential for overall water splitting but the weak oxygen evolution reaction (OER) catalytic activity hinders its development. Herein, urchin-like CoP/FeP@NF-1 was designed and fabricated on nickel foam via the hydrothermal and phosphorization to improve the OER performance and achieve efficient overall water splitting. The formation of CoP/FeP heterogeneous phases was successfully modulated the local electronic structure of CoP and increased the content of Co3+ species to enhance the catalytic activity of OER. Moreover, the urchin-like morphology and hydrophilic surface of CoP/FeP@NF-1 not only exposed more active sites but also promoted the transfer of electrolyte and products. So, CoP/FeP@NF-1 only required overpotentials of 67/153 mV for HER and 235/285 mV for OER to achieve the current density of 10/100 mA cm−2, respectively. Meanwhile, the assembled electrolyzer with CoP/FeP@NF-1 as the cathode and anode presented a cell voltage of 1.56 V to achieve 10 mA cm−2. In situ Raman characterization suggested that the formed oxyhydroxides during the OER process were the active phases. Furthermore, theoretical calculations revealed that the doped Fe accelerated HER by promoting the water dissociation and was also the main active site of OER. This work provided insights into the synthesis of efficient CoP-based bifunctional electrocatalysts for overall alkaline water splitting. Urchin-like CoP/FeP@NF-1 electrocatalyst with the hydrophilic surface and high Co3+ content was designed through doping engineering strategy. CoP/FeP@NF-1 showed high OER and HER catalytic activities due to its abundant exposed active sites, accelerated reaction kinetics and improved charge/mass transfer abilities. [Display omitted] •Urchin-like CoP/FeP@NF-1 with hydrophilic surface exposed more active sites and promoted mass transfer.•CoP/FeP@NF-1 with optimal local electronic structure and high Co3+ content showed high OER activity.•CoP/FeP@NF-1 exhibited excellent electrocatalytic performance for HER, OER and overall water splitting.