Furfural Oxidation Paired with Hydrogen Evolution on Nife/Ni Foam and Mxene-Supported Catalysts

The use of renewable energy sources for water electrolysis to generate environmentally friendly hydrogen faces challenges due to energy-intensive oxygen evolution reaction (OER) and potential risks of H₂ and O₂ mixing. To address these issues, a novel technique was proposed, replacing OER with electrocatalytic oxidative dehydrogenation (EOD) of aldehydes, producing carboxylic acids and hydrogen gas. Furfural oxidation was paired with hydrogen evolution to co-produce 2-furoic acid and hydrogen gas, achieving 100% efficiency with a 90% conversion rate in a H-type cell.

A two-dimensional early transition metal carbide (MXene) supported metal catalyst Co/Mo₂TiC₂T_x-700 was used as the cathode for hydrogen generation. MXenes offer advantages in catalysis due to their conductivity, stability, and high surface area. Mo₂TiC₂T_x as the substrate facilitated cobalt (Co) distribution, preserving active sites and optimizing metal supported interaction (MSI), influencing the electronic structure of Co for enhanced hydrogen evolution performance. The optimized Co/Mo₂TiC₂T_x-700 exhibited low overpotentials of 243.99 mV @ 100 mA cm^-2 and 320.56 mV @ 400 mA cm^-2 in H-type cell tests.

The NiFe/Ni foam prepared through an electrodeposition method served as an anode, which was paired with the Co/Mo₂TiC₂T_x-700 cathode (both to have an area of 2cm x 2cm) into a two-counterpart flow cell for furfural oxidation and hydrogen evolution. Co/Mo₂TiC₂T_x-700 outperformed commercial Pt/C electrodes with lower cell voltage (2.204V vs 2.249V) up to 100 mA cm^-2, while maintaining less than 90% H₂ faraday efficiency and having the same catalyst loading of 0.5 mg cm^-2. This substitution improved the efficiency of furfural oxidation, co-producing hydrogen gas and 2-furoic acid. The research successfully developed efficient non-noble metal catalysts, offering an economic and safe solution for hydrogen gas production along with production of 2-furoic acid from a top bio renewable feedstock.