Quantification of Active Sites and Elucidation of the Reaction Mechanism of the Electrochemical Nitrogen Reduction Reaction on Vanadium Nitride

Abstract

Despite recent intense interest in the development of catalysts for the electrochemical nitrogen reduction reaction (ENRR), mechanistic understanding and catalyst design principles remain lacking. In this work, we develop a strategy to determine the density of initial and steady‐state active sites on ENRR catalysts that follow the Mars–van Krevelen mechanism via quantitative isotope‐exchange experiments. This method allows the comparison of intrinsic activities of active sites and facilitates the identification and improvement of active‐site structures for ENRR. Combined with detailed density functional theory calculations, we show that the rate‐limiting step in the ENRR is likely the initial N≡N bond activation via the addition of a proton and an electron to the adsorbed N2 on the N vacancies to form N2H. The methodology developed and mechanistic insights gained in this work could guide the rational catalyst design in the ENRR.

Unveiling the Activity Origin of a Copper‐based Electrocatalyst for Selective Nitrate Reduction to Ammonia

“…Moreover, the preparation of hydrogen via the reforming of natural gas is accompanied by the emission of huge amounts of greenhouse gas . Thus, using water as a hydrogen source to prepare ammonia through electrocatalytic and photo(electro)catalytic nitrogen reduction has attracted increasing attention . However, the breaking of the N≡N triple bond (941 kJ mol −1 ) in nitrogen gas is challenging and the competitive hydrogen evolution reaction hampers the Faraday efficiency .…”

“…[14] Thus, using water as a hydrogen source to prepare ammonia through electrocatalytic and photo(electro)catalytic nitrogen reduction has attracted increasing attention. [15][16][17][18][19][20] However, the breaking of the N N triple bond (941 kJ mol À1 ) in nitrogen gas is challenging and the competitive hydrogen evolution reaction hampers the Faraday efficiency. [21][22][23] Simultaneously, vast amounts of nitrate (NO 3 À ) are discharged into the surface water and underground aquifer, threatening human health.…”

Promoting selective electroreduction of nitrates to ammonia over electron-deficient Co modulated by rectifying Schottky contacts

“…Nitrogen is a fundamental element to all human beings and planet ecosystems [1][2][3][4]. The reactive forms of nitrogen, such as ammonia (NH 3 ) [5,6], hydrazine (N 2 H 4 ) [7], nitride oxides (NO x ) [8], nitrite (NO 2 − ) and nitrate (NO 3 − ) [9], are crucial for the utilization of the nitrogen element. Particularly, ammonia, with an annual output of~200 million metric tons, has been widely used as a raw material for agricultural fertilizers and industrial productions [10,11].…”

Catalytically-active porous assembly with dynamic pulsating motion for efficient exchange of products and reagents

“…Nevertheless, the catalyst could be suspended immediately upon heating due to the block of active sites. The inactivation of transient state at high temperature was remarkably different from conventional catalysts that accelerated reaction upon heating 33,34 . Importantly, the inflation of tubules facilitated the exchange of products and reagents due to the increased entropy in inflated pores.…”