Solar-heating thermocatalytic H2 production from formic acid by a MoS2-graphene-nickel foam composite

Abstract

Sunlight driven formic acid decomposition has great potential to supply high-purity H₂ without consuming fossil fuel-derived energy. However, a trace amount of CO invariably exists in the obtained H₂ and the H₂ production rate is always lower than 278 mmol g⁻¹ h⁻¹. Here, we found that high quality MoS₂ grown on graphene decorated on Ni foam (Ni/G/MoS₂) was active and stable for H₂ production from thermocatalytic formic acid decomposition without CO presentation and first principles calculation confirmed that the perfect surface terminating sulfur of MoS₂ changed the reaction path of intermediates, thus inhibiting the production of CO. Furthermore, a reaction device constructed with Cu₂Se can heat catalysts to 120 and 260 °C under 0.25 kW m⁻² and 1 kW m⁻² (1 Sun) of irradiation, respectively. By using the system of the Cu₂Se based reaction device and Ni/G/MoS₂, a CO free H₂ production rate of 982 mmol g⁻¹ h⁻¹ was achieved under 0.6 Sun of irradiation, 3.5 times higher than the previous record of photocatalytic formic acid decomposition. Therefore, this work provides a new viewpoint for large scale CO free H₂ production in a sustainable and green way.