Metal–organic framework supported Au nanoparticles with organosilicone coating for high-efficiency electrocatalytic N2 reduction to NH3

Abstract

The development of electrocatalysts for nitrogen reduction reaction (NRR) at ambient conditions, with both high NH3 yield and Faradaic efficiency, is currently a great challenge. To this aim, a unique metal–organic framework (MOF) crystalline matrix with disulfide trimeric unit as the building block was in situ synthesized by integration of dynamic covalent chemistry and coordination chemistry. This MOF with high porosity and excellent stability could be used as a host material to encapsulate well-dispersed Au nanoparticles (NPs) with ultrafine size of 1.9 ± 0.4 nm. After surface modification of Au@MOF by using organosilicone, the hydrophobic-treated Au@MOF (HT Au@MOF) composite shows remarkable electrocatalytic performances for NRR, with the highest NH3 yield of 49.5 μg h–1 mgcat.–1 and the state-of-the-art Faradaic efficiency of 60.9% in water medium at ambient conditions. The favorable role of MOFs with functional sulfur groups on modulating the active Au sites and the great effect of hydrophobic coatings on suppressing the competitive hydrogen evolution reaction (HER) have been further demonstrated. This work provides a universal strategy to design composite electrocatalysts for high-efficient and long-term NH3 production.