Fast and Durable Dehydrogenation of Formic Acid over Pd-Cr(OH)3 Nanoclusters Immobilized on Amino-Modified Reduced Graphene Oxide

Formic acid, attractive as a renewable and safe liquid organic hydrogen carrier (LOHC), can be obtained by biomass conversion and CO2 hydrogenation with green hydrogen. The efficient and durable catalysts for formic acid dehydrogenation (FAD) are beneficial in the industry. Herein, Cr(OH)3-promoted Pd nanoclusters (NCs) (i.e., 1.6 nm) immobilized on amino-modified reduced graphene oxide (NH2-rGO) were successfully prepared through a simple wet-chemical approach. The obtained Pd- Cr(OH)3/NH2-rGO catalyst exhibits excellent catalytic activity and 100% hydrogen selectivity for CO-free FAD, giving a high turnover frequency of 2519.5 h-1 at 323 K, outperforming most reported Pd-based heterogeneous catalysts. Especially, the catalyst possesses robust durability toward FAD with no significant decline in activity and aggregation of metal NCs even after 10 cycles. The superior performance of the catalyst may be ascribed to the well distributed Pd-Cr(OH)3 NCs, the strong electronic coupling of Pd with Cr(OH)3, the synergetic interaction of Pd-Cr(OH)3 with NH2-rGO, and the promotion effect of amino group. The reaction mechanism of FAD was explored based on the isotope experiments. This work provides insights into designing an effective and durable heterogeneous catalyst for dehydrogenation of LOHC.

Automated summary

In this study, Cr(OH)3-promoted Pd nanoclusters immobilized on amino-modified reduced graphene oxide were prepared and exhibited excellent catalytic activity and selectivity for CO-free formic acid dehydrogenation. The catalyst showed durable performance even after 10 cycles, which can be attributed to the well distributed Pd-Cr(OH)3 nanoclusters, strong electronic coupling with Cr(OH)3, synergetic interaction with NH2-rGO, and the promotion effect of amino group. This work provides insights into designing an effective and durable heterogeneous catalyst for dehydrogenation of LOHC.