In-situ synthesis of bifunctional N-doped CoFe2O4/rGO composites for enhanced electrocatalysis in hydrogen and oxygen evolution reactions

초록

The development of cost-effective and efficient materials for electrochemical water splitting using non-noble metal oxide is a promising strategy to promote clean energy and mitigate environmental issues. In this study, we synthesized N-doped CoFe2O4 (NCF) and various wt% rGO-loaded N-doped CoFe2O4 (x = 1 %, 3 %, and 5 %; denoted as NCFRx) using a hydrothermal method. Subsequently, the NCF and NCFR3 samples were annealed at four different temperatures (y = 550, 600, 650, and 700 degrees C; denoted as NCFR3-y). FE-SEM, TEM, and XPS studies revealed a strong interface between rGO nanosheets and N-doped CF, acting as electron transport carriers that enhance performance in hydrogen and oxygen evolution reactions (HER and OER). The electrochemical evaluation of the prepared materials was carried out in a 1.0 M KOH electrolyte. The nickel foam (NF) electrode supported by the NCFR3-650 composite demonstrated excellent and stable electrocatalytic performance with a minimum overpotential of 73 mV and 170 mV at a current density of 10 mA/cm2 for HER and OER, respectively, and achieved excellent faradaic efficiencies of 91.01 % for OER and 90.48 % for HER. These results confirmed that the NCFR3-650@NF composite catalyst was comparable to standard Pt/C and IrO2, exhibiting lower overpotential and Tafel slope at a current density of 10 mA/cm2. The double layer capacitance (Cdl) of NCFR3-650@NF (7.70 mF/cm2) was higher than that of other electrocatalysts, indicating a large electrochemically active surface area. The structural properties of NCFR3-650@NF contributed to improved stability during long-term HER and OER analysis. Therefore, the developed NCFR3-650@NF electrocatalyst is a promising alternative to noble metal-centered systems for water splitting, offering overall high efficiency.

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