Photoelectrosynthesis of 2,5-Furandicarboxylic Acid (FDCA) and Impact of Band-Gap on Conversion Yield

Electrooxidation of water to oxygen is a kinetically slow reaction; hence, a large overpotential is required to drive this process at a desired rate and to generate adequate electrons for hydrogen reduction at a platinum cathode. A possible alternative is to replace water with another species whose oxidation needs lower overpotentials. In this regard, electrooxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA) has shown fast kinetics at low overpotentials Figure 1). 1 Furthermore, this reaction features great industrial significance; HMF is a byproduct of the food industry (estimated annual production of 50 million tons) and its conversion to FDCA is an important process in the field of degradable polymers. 2,3 FDCA is a cheap and green alternative for polyethylene terephthalic acid (PET) that has been used for fabrication of plastics. 4–6 In the present work, we studied the electro- and photoelectrooxidation of HMF to FDCA with application of an anode made of Ni x Cu 1-x WO 4 (0 ≤ x ≤ 0.1). In experiment 1, electrooxidation of HMF was carried out in the absence of light. The conversion yield has been reported for this experiment by measurement of the amount of hydrogen gas evolved and FDCA formed at the end of the electrolysis. Finally, the yield of the reaction was correlated to the doping amount of copper incorporated within the host of nickel tungstate. For photoelectrochemical conversion of HMF, a similar setup to experiment 1 has been utilized; however, electrolyses were carried out in the presence of light (experiment 2). Conversion yield and oxidation overpotential in both experiments have been compared to evaluate the effect of doping on the photoelectrochemical properties of modified nickel tungstate. Present data revealed that lower oxidation overpotential is needed in experiment 2 in comparison with experiment 1. Moreover, we observed that, by enhancement of the copper amount (experiment 2), conversion yield was improved significantly. References Kubota, S. R.; Choi, K.-S. ChemsusChem . 2018 , 11 , 2138. Rosatella, A. A.; Simeonov, S. P.; Raquel, F. M.; Afonso, C. A. M. Green Chem . 2011 , 13 , 754. Howard, J.; Rackemann, D. W.; Bartley, C.; Samori, C.; Doherty, W. O. S. ACS Sustainable Chem. Eng. 2018 , 6 , 4531. Li, K.; Mengmeng, D.; Ji, P. ACS Sustainable Chem. Eng. 2018 , 6, 5636 . Xu, S.; Zhou, P.; Zhang, Z.; Yang, C.; Zhang, B.; Deng, K.; Bottle, S.; Zhu, H. ACS Sustainable Chem. Eng. 2017 , 139 , 14775. Macedo, N. G.; Gouveia, A. F.; Roca, R. A.; Assis, M.; Garcia, L.; Andres, J.; Leite, E. R.; Longo, E. J. Phys. Chem. C 2018 , 122 , 866. Figure 1