Strong metal-support interaction of Pd/CeO2 enhances hydrogen production from formic acid decomposition

Abstract

Strong metal support interaction (SMSI) between metals and oxides is considered an efficient manner to promote catalytic performance by the electron transfer, stabilizing the active metals, and the formation of intermediate phases, etc. Herein, we synthesized Pd NPs on cube and truncated cube ceria (Pd/CeO2-c and Pd/CeO2-tc) to study the effect of SMSI on formic acid (HCOOH) decomposition (FAD) to H2. Pd/CeO2-tc exhibited the excellent catalytic performance for FAD with a turnover frequency of 2850 h−1 at 323 K, which was 3.41 times than that of Pd/CeO2-c. Detailed studies demonstrated that the enhanced FAD performance of Pd/CeO2-tc was due to SMSI between Pd NPs and CeO2-tc, with lower electron cloud density of the surface Pd species, higher surface oxygen vacancies (OV) ratio, and more Pd0–OV–Ce3+ species than Pd/CeO2-c. Mechanistic studies indicated that Pd/CeO2-tc with SMSI facilitated the generation of bidentate formate complex with HCOOH (HCOOH–HCOO*) and the evolution from HCOOH–HCOO* to HCOO*, CO2, and H2, where HCOOH–HCOO* should be the more critical intermediate than HCOO* for FAD.