CO2 hydrogenation to HCOOH catalyzed by aqueous Pd needle assembly.

Carbon dioxide (CO2) conversion to liquid fuels has attracted great attention due to the current environmental concerns and energy crisis. However, the selective conversion of CO2 to target liquids is formidably challenging due to the chemical inertness of CO2. We theoretically and experimentally confirm that the bending of Pd-Pd bond can breaks the asymmetric potential well and facilitate CO2 adsorption. We have successfully synthesized a new class of Pd nanoneedles via a "close edges and open corners" process, with a magic angle of 60o between the main trunk and branch, and realized the selective CO2 hydrogenation to formic acid (HCOOH) at room temperature in water. Impressively, a HCOOH productivity of ~250 mmol g-1 in 100 h while maintaining HCOOH selectivity over 99%. This work bridges nanostructure design and catalytic application, which may open a new avenue for selective CO2 conversion in an elegant manner.