Dual-functional Ni and Co oxide-doped carbon nanocomposite: an effective catalyst for electrochemical water splitting and CO2 utilization

Abstract

The catalytic activation of small molecules is an excellent approach for scientific and technological developments. The production of green hydrogen and fine chemicals through water splitting and carbon dioxide fixation, respectively, is highly effective and eco-friendly; it can meet the requirements for energy economy and sustainability. Transition metal-derived nanomaterials are considered very efficient catalysts. Herein, we developed a metal oxides@carbon (NCC) nanocomposite derived from a bimetallic (Ni/Co) MOF as a multifunctional catalyst. The NCC catalyst was successfully investigated for CO₂ fixation, oxygen evolution, and hydrogen evolution reactions. The NCC nanocomposite catalyst shows a noticeable CO₂ cycloaddition to epoxide efficiency of 74–99.9% at 50–100 °C under 1.97 atm in 24 h. NCC exhibits low overpotentials (η₁₀) for an alkaline (1 M KOH) medium OER and HER, i.e., 310 and 200 mV with Tafel slopes of 76 and 117 mV dec⁻¹, respectively. Similarly, for an acidic (0.1 M H₂SO₄) medium HER, η₁₀ = 118 mV and Tafel slope = 47 mV dec⁻¹. High electron conductivity with very low charge transfer resistance is observed (R_ct/Ω = 0.55 for the OER_alkaline, 8.13 for the HER_alkaline, and 0.824 for the HER_acidic). Bulk electrolysis revealed stable performance for 10–15 h at η₁₀ in each case without any major changes in the structural morphology of NNC. These results show the synergy of the active sites for achieving superior catalytic properties, presenting NCC as a suitable candidate for sustainable energy applications.