Tetrafunctional electrocatalyst for oxygen reduction, oxygen evolution, hydrogen evolution, and carbon dioxide reduction reactions

Abstract

BackgroundThe development of novel electrocatalysts with high efficiency, low cost, and high stability to replace platinum group metal (PGM) electrocatalysts is essential for realizing sustainable energy applications. MethodsIn this study, we synthesized a tetrafunctional electrocatalyst comprising NiFe layered double-hydroxide (LDH) nanosheets anchored on carbon-nanotube-grafted (CNT), Co3O4-embedded, and N-doped porous carbon matrices (NC) derived from zeolitic imidazolate frameworks (NiFe LDHCNT-Co3O4/NC). Significant FindingsThis electrocatalyst exhibited superior performance to PGM electrocatalysts in the oxygen reduction reaction (ORR), oxygen evolution reaction (OER), hydrogen evolution reaction (HER), and carbon dioxide reduction reaction (CO2RR). The linear sweep voltammetry study showed that the NiFe LDHCNT-Co3O4/NC demonstrated superior performance (Eonset = 0.85 V and E1/2 = 0.79 V for ORR; Ej=10 = 1.63 V for OER; overpotential = 0.84 V) comparing to the benchmarks of Pt/C and RuO2. A rechargeable Zn–air battery (ZAB) is used to verify the performance of the developed electrocatalyst in the ORR and OER; the ZAB exhibited an ultralow charge–discharge voltage gap (0.74 V) and excellent stability (104 cycles, >1600 h@10 mA cm−2). Overall water splitting (OWS) is performed to verify the performance of the developed electrocatalyst in the OER and HER. The adopted OWS device exhibited a long and stable process (1.6 V@10 mA cm−1, 700 h). CO2 conversion is investigated for evaluating the HER and CO2RR, and an 80% faradaic efficiency of CO production and high stability are obtained (166 mA cm−2@−1.09 V). We think that the synergistic effect of the NiFe LDHs, Co3O4 nanoparticles, and nitrogen-doped carbon electrocatalyst contributes to the excellent electrocatalytic performance of NiFe LDHCNT-Co3O4/NC in the aforementioned reactions. The hydrophilic NiFe LDHs and highly mesoporous carbon matrices provide a favorable ionic pathway for achieving rapid diffusivity and efficient mass transfer while the CNTs and carbon frameworks enhance the electrical conductivity during redox processes