Efficient Electrochemical Reforming of Biomass Carbohydrates to Syngas Catalyzed by Lacunary Phosphomolybdic Acid

Syngas (H2, CO) is a common industrial feedstock usually produced by coal gasification at high temperatures. Herein, we present an electro-coupled-chemical reforming method that converts renewable biomass carbohydrates into syngas by using lacunary phosphomolybdic acid (MoPA) as the catalyst under mild conditions (pH = 5, <100 °C). The lacunary MoPA derives from the typical Keggin structure but acts as an efficient carbohydrate C–C bond cleavage catalyst due to its active defect sites. It degrades biomass carbohydrates into C1 compounds, such as CO and CO2, with the highest kinetic rate being 22 times higher than the initial Keggin catalyst. The produced CO2 can be self-supplied into the cathode side with coupled CO2 electrocatalytic reduction for syngas yield over the typical AgPd catalyst, and simultaneously, the lacunary MoPA catalyst is regenerated at the anode side with a significant electric energy saving. In the continuous flow running for 3600 s, the current density reaches 50 mA cm–2 at −1.6 V, and the syngas can be obtained with a tunable H2:CO ratio from 2.96 to 1. Compared with conventional syngas production, the electrochemical route provides a full carbon conversion of carbohydrate biomass into syngas with the advantages of a low reaction temperature and near-neutral conditions.