Apart from ubiquitous biomass sources, the greenhouse gas CO2 can be used as an abundant carbon source to produce energy-rich chemicals such as CO, formate, hydrocarbons or alcohols. However, photo-and electroreduction of CO2 are predominantly performed in the presence of pure CO2, where concentrated CO2 streams have to be generated involving additional energy input. To alleviate the energy demand of the process, it is desirable to perform catalytic reactions at lower CO2 concentrations (e.g., ≤ 20% CO2). The challenge of using low concentration CO2 streams lies in maintaining high product selectivity and catalytic activity compared to reactions employing pure CO2 streams. Molecular CO2 reduction catalysts display an increased product selectivity compared to most heterogenous electro-or photocatalysts. An attractive approach to utilise biomass and CO2 together is their simultaneous conversion in photo-or electrocatalytic processes. This strategy opens the possibility to couple biomass oxidation with CO2 reduction in a single process driven by sunlight or renewable electricity. The coupling of productive half-reactions thereby allows the conversion of a solid and a gaseous waste stream into valuable products such as CO, syngas, formate and aromatic chemicals, which can be more attractive than conventional systems performing overall water splitting to generate H2 and O2 from water. Additionally, the oxidation of biomassderived substrates is thermodynamically less demanding than water oxidation, thereby facilitating the catalytic conversions, as well as the generation of added value products. This combined approach also allows for the isolation of products in different phases and compartments, which can help with product separation. Conventional approaches such as water splitting generate explosive H2 and O2 mixtures in the reactor headspace.