Electronic State and Microenvironment Modulation of Metal Nanoparticles Stabilized by MOFs for Boosting Electrocatalytic Nitrogen Reduction

Modulation of the local electronic structure and microenvironment of catalytic metal sites plays a critical role in electrocatalysis, yet remains a grand challenge. Herein, PdCu nanoparticles with an electron rich state are encapsulated into a sulfonate functionalized metal-organic framework, UiO-66-SO3H (simply as UiO-S), and their microenvironment is further modulated by coating a hydrophobic polydimethylsiloxane (PDMS) layer, affording [email protected]@PDMS. This resultant catalyst presents high activity toward the electrochemical nitrogen reduction reaction (NRR, Faraday efficiency: 13.16%, yield: 20.24 µg h−1 mgcat.−1), far superior to the corresponding counterparts. Experimental and theoretical results jointly demonstrate that the protonated and hydrophobic microenvironment supplies protons for the NRR yet suppresses the competitive hydrogen evolution reaction reaction, and electron-rich PdCu sites in [email protected]@PDMS are favorable to formation of the N2H* intermediate and reduce the energy barrier of NRR, thereby accounting for its good performance.