Constructing an oxide-fluoride heterojunction supported on carbon cloth as a highly active and stable catalyst for enhancing overall water-splitting

• Published in: International journal of hydrogen energy 2024-02, Vol.57, p.473-480
• Main Authors: Ji, Pengxia, Zheng, Deyong, Jin, Huihui, Liao, Yucong
• Format: Article
• Language: English
• Subjects: More active sites; Overall water-splitting; Oxide-fluoride heterojunction; Preferable kinetic process
• ISSN: 0360-3199; 1879-3487
• DOI: 10.1016/j.ijhydene.2024.01.038

To realize large-scale production of hydrogen by water electrolysis, the development of inexpensive and high-performance catalysts is urgently needed. Herein, we developed an oxide-fluoride (Co3O4–CoF2) heterojunction catalyst with mooncake shape morphology supported on carbon cloth (CC) used as a bifunctional water electrolysis catalyst in 1 M KOH. The obtained Co3O4–CoF2 heterojunction exhibits a preferable kinetic process and more active sites than its mono components Co3O4 and CoF2, which only needs 46 mV for HER and 169 mV for OER at 10 mA cm−2 comparable to benchmark Pt/C and even super to benchmark IrO2. Meanwhile, it also demonstrates long-term stability, maintaining activity for 100 h for both HER and OER. Importantly, when assembled as a water electrolysis device, only a low cell voltage of 1.45 V is required to achieve the current density of 10 mA cm−2. Meanwhile, it can output continuous and stable current densities of 10, 100, and 10 mA cm−2 approaching 24 h under constant cell voltages of 1.47, 1.69, and 1.47 V, respectively. Therefore, the oxide-fluoride heterojunction catalyst unambiguously is a type of ideal bifunctional water electrolysis catalyst in alkaline media. The Co3O4–CoF2 heterojunction is a type of ideal bifunctional water electrolysis catalyst in alkaline media that exhibits a preferable kinetic process and more active sites than those of mono components. It not only possesses Pt-like and exceeds IrO2 activity but also displays exceptional stability up to 100 h for both HER and OER. The assembled Co3O4–CoF2||Co3O4–CoF2 device also shows an ultralow cell voltage of 1.45 V at 10 mA cm−2 and long-term stability of 72 h, as well as 100 % Faradaic efficiency. [Display omitted] •Co3O4–CoF2 exhibits preferable kinetic process and more active site than mono component.•Co3O4–CoF2 displays excellent activity comparable to Pt/C and exceeding IrO2.•Co3O4–CoF2.||Co3O4–CoF2 device only needs a low cell voltage of 1.45 V at 10 mA cm−2•The device shows outstanding stability of 72 h and close to 100 % Faradaic efficiency.