Insights into hydrogen generation from formic acid on PtRuBiO_x in aqueous solution at room temperature

摘要

The catalytic dehydrogenation of formic acid (HCOOH) on heterogeneous catalysts in aqueous solution to produce CO-free H_2 has received intense investigation due to its promising application in portable power devices. In this work, we present a study on the mechanism of HCOOH dehydrogenation on the PtRuBiO_x catalyst using density functional theory (DFT) calculations supported by complementary experiments. The catalyst's activity at room temperature was clarified by investigating HCOOH dehydrogenation on PtRu alloy and Bi_2O_3 surface with a focus on the key reaction steps. The PtRu with different alloying degree was modeled by a four-layer p (2 × 2) unit cell with Pt-skin and leaving Ru atoms in the second and the third layer based on the surface energy and the formation energy. The Bi_2O_3 surface was represented by the most stable (111) surface of δ-Bi_2O_3. Based on the computational and experimental results, a reaction pathway for HCOOH dehydrogenation on the PtRuBiO_x in aqueous solution was proposed. The results suggest that the promotion of HCOOH dissociation on the Bi_2O_3 surface and the ligand effect between Pt and Ru are responsible for the activity of PtRuBiO_x toward HCOOH dehydrogenation in aqueous solution at room temperature. Furthermore, the PdBiO_x system was also prepared and investigated as a catalyst for HCOOH decomposition at room temperature. The catalytic behavior of PdBiO_x for HCOOH dehydrogenation in aqueous solution was compared with that of the PtRuBiO_x.