(551h) Energy-Saving Electrochemical Hydrogen Production Coupled with Value-Added Isobutanol Oxidation to Isobutyric Acid

The wide application of electrochemical hydrogen production is hindered by the high energy consumption of conventional water electrolysis. One of the key reasons lies in the high overpotential caused by the sluggish kinetics of anodic Oxygen Evolution Reaction (OER). In addition, the low-value oxygen product cannot be utilized effectively, thus increasing the hydrogen production costs. Replacing OER with thermodynamically more favorable organics oxidation reactions can reduce electrolysis voltage. More importantly, many anodic organics oxidation reactions can produce value-added chemicals under mild condition without any external oxidant.

Isobutanol is a kind of high energy density biofuel which can be produced by the fermentation of cellulose. Isobutyric acid, as the oxidation product of isobutanol, is an important chemical intermediate which is widely used in food, fragrance, and pharmaceutical industry. Hence, the selective transformation of isobutanol to isobutyric acid via electrochemical oxidation is a promising way to upgrade biomass to valuable fine chemicals.

In this work, we demonstrate the feasibility of coupling anodic isobutanol value-added oxidation with cathodic hydrogen evolution reaction. The Nickel-based anode electrocatalyst prepared by a facile electrodeposition method can achieve high selectivity and faradic efficiency (>90%) toward isobutyric acid. Compared with conventional water electrolysis in alkaline media, the introduction of isobutanol can reduce the cell voltage by ≈200mV under the same current density. Moreover, the formation of oxygen can be avoided, improving hydrogen purity and process safety. In this way, the electrochemical reactor design can be simplified to membrane-less structure. In conclusion, we design an energy-saving electrochemical system for coproduction of hydrogen and value-added chemicals from biomass. Combing renewable energy storage and electrified fine chemicals production, the system is applicable for distributed scenarios.