Electrochemical oxidation and advanced oxidation processes using a 3D hexagonal CoO array anode for 4-nitrophenol decomposition coupled with simultaneous CO conversion to liquid fuels via a flower-like CuO cathode.

A novel electrocatalytic system was developed to realize one-pot conversion of organic pollutants into liquid fuels such as methanol (CHOH) and ethanol (CHOH). The process combines the catalytic oxidation of organic pollutants with electrocatalytic reduction of CO. We first coupled the electrocatalytic process with SO-based advanced oxidation processes (AOPs) for the degradation of 4-nitrophenol (4-NP) using a 3D-hexagonal CoO anode. In this step, 4-NP was mineralized to CO, and then the CO was converted to CHOH and CHOH by electrocatalytic reduction using a flower-like CuO cathode. The experimental results show the destruction of 4-NP (60 mL, 10 mg/L) can be as high as 99%. In addition, the yields of CHOH and CHOH were 98.29 μmol/L and 40.95 μmol/L, respectively, which represents a conversion of 41.8% of 4-NP into liquid fuels; the electron efficiency was 73.1%. In addition, we found that 3D-hexagonal arrays of CoO with different morphologies can be obtained by adding different amounts of urea. We also investigated the formation mechanism of novel 3D-hexagonal CoO arrays for the first time. A mechanism was proposed to explain the electrocatalytic steps involved in the conversion of 4-NP to CHOH and CHOH and the synergetic effects between AOPs and electrocatalysis.