Additive-free photocatalyzed Hydrogen production from formic acid aqueous solution on molybdenum carbides

Abstract

Hydrogen energy is the answer to the global energy crisis in the close future. Hydrogen is generable from various methods including electrolysis, steam methane reforming, thermal decomposition and photocatalyzed generation from all sources. Mo₂C-related catalysts are highly active in hydrogen generation from formic acid at elevated temperatures. In this work, Mo₂C and Co-doped Mo₂C nanoparticles present high activity in hydrogen generation from formic acid under ultraviolent light at room temperature without any additive. The addition of Mo₂C and Co-doped Mo₂C nanoparticles in photocatalyzed formic acid decomposition improves the H₂ productivity and selectivity greatly and reduces non-H₂ productive formic acid consumption under ultraviolet light. A H₂ production of 2890 μmol·g⁻¹·h⁻¹ yielded on 5-CoMo₂C. The H₂ selectivity of the catalyzed formic acid decomposition is 5 times that of the non-catalyzed reaction under the same condition. The complete formation of Mo₂C phase is key to the high photocatalytic activity, owning to both prolonged calcination time and Co doping. With Co doping, the Mo₂C phase formation was completed within a much shorter calcination time, and the obtained catalysts present higher H₂ productivity compared to non-doped catalysts. The use of Mo₂C in photocatalyzed H₂ production provides a new low-cost H₂ production method and in line with pollution control and resourceful utilization of formic acid, which fits the prospect of safe, clean and additive-free H₂ generation approach.

Graphical abstract