Reaction pathways derived from DFT for understanding catalytic decomposition of formic acid into hydrogen on noble metals

Formic acid decomposition on noble metals is considered to be a potential method to produce CO-free hydrogen at near ambient temperatures. However, the reaction mechanism, as well as the key points, for HCOOH decomposition on noble metals in aqueous solution remains unclear at microscopic level. In the present work, we employed density functional theory (DFT) calculation to investigate HCOOH decomposition in gas and aqueous phases on four common noble metals (Pt, Pd, Rh, and Au). Based on the present theoretical calculation results and experimental results being available in literature, two reaction pathways were proposed to understand gas- and aqueous-phase HCOOH decomposition on the noble metals. The key points that determine the activities of the metals toward HCOOH decomposition into CO2 and H2 in aqueous solution are clarified. Furthermore, the proposed reaction mechanism can be well extended to interpret the excellent activity of Ag–Pd core–shell bimetallic catalyst for HCOOH decomposition in aqueous solution. It is expected the present reaction mechanisms would enable us to rationally design more active heterogeneous catalysts for HCOOH decomposition into CO-free H2 at relatively low temperatures.

Graphical abstractTwo reaction pathways were derived from DFT calculations and could be used to understand gas- and aqueous-phase HCOOH decomposition on noble metals. The key points for the reaction on the noble metals were clarified. This would enable us to rationally design more active heterogeneous catalyst for HCOOH decomposition to produce CO-free H2 at near ambient temperatures.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Reaction networks of HCOOH on several noble metals were studied by DFT. ► Two reaction pathways were proposed for HCOOH decomposition on the metals. ► The proposed reaction pathways can explain the experimental results. ► The key points for HCOOH decomposition into H2 were clarified. ► The study can be used to rationally design catalysts for HCOOH decomposition.