ELECTROCHEMICAL CONVERSION OF LOW VALUE BIOMASS OXYGENATES INTO HYDROGEN AND CARBON DIOXIDE
Advancing sustainable pathways to upcycle wastewater resources containing oxygenates into hydrogen (H2) and carbon dioxide (CO2), with the potential of capturing and converting CO2 into value-added products, unlocks new pathways to access low carbon H2 as a clean energy carrier. Significant reduction in the cost of renewable electricity over the course of the past decade now sets the stage for harnessing low value wastewater resources as a resource for H2. Electrochemical oxidation of oxygenates into CO2 has several unique features: (i) First, this pathway is thermodynamically more favorable compared to Electrochemical reduction of CO2 to oxygenates. (ii) Second, the breakdown of oxygenates into *CO intermediates is a primary constraint but the associated electron transfer assists with H2 generation. (iii) Third, this pathway does not require the high temperatures needed for steam methane reforming (SMR) and the possibility of capturing and converting CO2 into value-added products has the potential to close the carbon cycle and in specific scenarios, result in net negative emissions coupled to H2 generation. In this study, methanol is used as a biomass oxygenate precursor mixed in water and KOH to increase the electrical conductivity of the electrolyte. To enhance the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), nickel sulfide (NiS) catalyst is used as the working electrode and platinum is used as the counter electrode. These electrochemical conversion pathways were carried out at temperatures below 100 ºC and at different voltage conditions to investigate their influence on H2 yields from biomethanol. The influence of 2-electrode and 3-electrode systems on the biomethanol to produce H2 and CO2 is investigated. Our future work is oriented towards expanding these pathways to include the deconstruction of heterogeneous oxygenate streams for co-producing H2 and CO2, demonstration of the capture and conversion into value-added solid products, and identification of the pathways and physico-chemical processing conditions that result in net negative carbon removal scenarios coupled to H2 conversion.