Recent progress, trends, and new challenges in the electrochemical production of green hydrogen coupled to selective electrooxidation of 5-hydroxymethylfurfural (HMF).

The production of clean electrical energy and the correct use of waste materials are two topics that currently concern humanity. In order to face both problems, extensive work has been done on the electrolytic production of green H 2 coupled with the electrooxidative upgrading of biomass platform molecules. 5-Hydroxymethylfurfural (HMF) is obtained from forest waste biomass and can be selectively oxidized to 2,5-furandicarboxylic acid (FDCA) by electrochemical pathways. FDCA is an attractive precursor to polyethylene furanoate (PEF), with the potential to replace petroleum-based polyethylene terephthalate (PET). An integrated electrochemical system can simultaneously produce H 2 and FDCA at a lower energy cost than that required for electrolytic water splitting. Here, the benefits of the electrochemical production of H 2 and FDCA over other production methods are presented, as well as the innovative applications of each reaction product and the advantages of carrying out both reactions in a coupled system. The recently reported progress is disclosed, through an exploration of electrocatalyst materials used in simultaneous production, including the use of nickel foams (NF) as modification substrates, noble and non-noble metals, metal non-oxides, metal oxides, spinel oxides and the introduction of oxygen vacancies. Based on the latest trends, the next challenges associated with its large-scale production are proposed for its implementation in the industrial world. This work can offer a guideline for the detailed understanding of the electrooxidation of HMF towards FDCA with the production of H 2 , as well as the design of advanced electrocatalysts for the sustainable use of renewable resources.