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<\/figure><\/div>\n\n\n\n A distinct reaction intermediate was detected, and the decarboxylation onset potential was determined to be 2.2\u20132.3 V versus the reversible hydrogen electrode (RHE). Following the mechanistic studies and electrode optimization, a two-step bio-electrochemical process was established for ethylene production using succinic acid sourced from food waste. The initial step of this integrated process involves microbial hydrolysis\/fermentation of food waste into aqueous solutions containing succinic acid (0.3 M; 3.75 mmol per g bakery waste). The second step is the electro-oxidation of the obtained intermediate succinic acid to ethylene using a flow setup at room temperature, with a productivity of 0.4\u20131 \u03bcmol ethylene cmelectrode<\/sub>\u20132<\/sup>\u00a0h\u20131<\/sup>. This approach provides an alternative strategy to produce ethylene from food waste under ambient conditions using renewable energy.<\/p>\n\n\n\n Electrochemical processes driven by renewable energy sources hold promise in the chemical industry to reduce fossil fuel dependence and associated CO2<\/sub>\u00a0emissions.\u00a0(1\u22123)<\/a>\u00a0Alternative sustainable resources for fuel and chemical production can also contribute to attaining a net-zero carbon economy. Biomass and waste substrates (food waste, plastics, or mixed waste streams) are cheap and ubiquitous, making them an attractive alternative source to produce platform chemicals.\u00a0(4\u22126)<\/a>\u00a0Carboxylic acids are important intermediates in the upgrading of biomass and waste substrates to higher-value chemicals, as they can be obtained efficiently via various pathways.\u00a0(7,8)<\/a>\u00a0The chemical conversion of carboxylic acids using electrochemistry has been investigated intensively since the discovery of the Kolbe reaction, which is the oxidative dimerization of carboxylic acids to form hydrocarbons.\u00a0(9\u221211)<\/a><\/p>\n\n\n\n Several approaches are known to convert carboxylic acids (e.g., levulinic acid, hexanoic acid) into longer-chain aliphatic compounds (fuels) or high-value organic chemicals,\u00a0(3,4,12\u221214)<\/a>\u00a0but the carboxylic acids need to be produced and purified before electrochemical conversion. Electro-biorefinery concepts combine biological and electrochemical processes to facilitate the conversion of complex renewable feedstocks into high-value chemicals.\u00a0(8,12,15)<\/a>\u00a0Long-chain alkanes, such as decane, obtained from the Kolbe reaction, are suitable transportation fuels, but they are not ideal substrates for the chemical industry, due to their lack of chemical functional groups.\u00a0(16)<\/a>\u00a0Therefore, other non-Kolbe products, such as alkenes are more desirable. <\/p>\n\n\n\n Among others, ethylene, with a yearly production of 170 million tons, serves as a key intermediate owing to its high industrial demand and can be further processed into a variety of different chemicals through established routes, such as ethylene oxide, styrene, or vinylchloride.\u00a0(17\u221219)<\/a>\u00a0The electrochemical conversion of carboxylic acids into alkenes has been described as a side reaction in the Kolbe process, but alkenes have rarely been the target product in these approaches.\u00a0(20\u221223)<\/a>\u00a0Recently, the conversion of dicarboxylic acids into alkenes has been reported,\u00a0(24,25)<\/a>but little is known about the mechanism of this reaction and the factors influencing the overall process. A deeper insight is necessary to enable the efficient and selective production of alkenes.<\/p>\n\n\n\n In this work, we demonstrate a combined bio-electrochemical process that allows the conversion of food waste into ethylene, with succinic acid as the central intermediate. The first biocatalytic step utilizes solid-state and aqueous-phase fermentation for the conversion of food waste into succinic acid, whereas the subsequent electrocatalytic step transforms the succinic acid intermediate to ethylene. This approach establishes an alternative and renewable pathway for the generation of ethylene from waste substrates.\u00a0(19)<\/a>\u00a0In this study, different approaches for material characterization and electroanalytical techniques were applied to evaluate the structure\u2013activity relationships for the oxidative decarboxylation of succinic acid on carbon electrode materials. A reaction mechanism was proposed for this decarboxylation reaction using quantum chemical calculations, supported by electron paramagnetic resonance (EPR) and\u00a0in situ<\/em>\u00a0infrared (IR) spectroscopy.<\/p>\n\n\n\n …<\/p>\n\n\n\nIntroduction<\/h3>\n\n\n\n