Helical copper-porphyrinic framework nanoarrays for highly efficient CO2 electroreduction

In recent years, metal-organic frameworks (MOFs) have been extensively investigated as electrocatalysts due to their highly efficient electroreduction of CO2. Herein, the electrocatalytic CO2 reduction reaction was investigated by growing helical Cu-porphyrinic MOF Cu meso-tetra(4-carboxyphenyl)porphyrin (TCPP) on Cu(OH)2 nanoarrays (H-CuTCPP@Cu(OH)2) using a sacrificial template method. The electrocatalytic results showed that the H-CuTCPP@Cu(OH)2 nanoarrays exhibited a high acetic acid Faradaic efficiency (FE) of 26.1% at −1.6 V vs. Ag/Ag+, which is much higher than the value of 19.8% obtained for non-helical CuTCPP@Cu(OH)2 (nH-CuTCPP@Cu(OH)2). The higher efficiency may be because space was more effectively utilized in the helical MOF nanoarrays, resulting in a greater number of active catalytic sites. Furthermore, in situ diffuse reflectance infrared Fourier transform spectra showed that the H-CuTCPP@Cu(OH)2 nanoarrays have much stronger CO linear adsorption, indicating a better selectivity of acetic acid than that of nH-CuTCPP@Cu(OH)2. In this study, we develop new helical nanomaterials and propose a new route to enhance the reduction of CO2.