An Overview on Noble Metal (Group VIII)‐based Heterogeneous Electrocatalysts for Nitrogen Reduction Reaction

Abstract

The typically the Haber‐Bosch process of nitrogen (N2) reduction to ammonia (NH3) production, expends a lot of energy, resulting in severe environmental issues. Electro‐catalytic N2 reduction to NH3 formation by renewable resources is one of the effective ways to settle the issue. However, the electro‐catalytic performances and selectivity of catalysts for electrochemical nitrogen reduction reaction (NRR) are very low. Therefore, it is of great significance to develop more efficient electro‐catalysts to satisfy the needs of practical use. Among the reported catalysts, those based on Group VIII noble metals heterogeneous catalysts display excellent NRR activities and high selectivity because of their good conductivity, rich active surface area, unfilled d‐orbitals, and the abilities with easy adsorption of reactants and stable reaction intermediates. Herein, we will introduce the progress of Group VIII precious metals heterogeneous catalysts applied in the electrocatalytic N2 reduction reaction. Then single precious metal electrocatalysts, precious metal alloy electrocatalysts, heterojunction structure electrocatalysts, and precious metal compounds based on the strategies of morphology engineering, crystal facet engineering, defect engineering, heteroatom doping, and synergetic interface engineering will be discussed. Finally, the challenges and prospects of the NH3 synthesis have been put forward. In the review, we will provide helpful direction to the development of effective electro‐catalysts for catalytic N2 reduction reaction.

Elemental 2D Materials: Solution‐Processed Synthesis and Applications in Electrochemical Ammonia Production

“…Noble metals such as Pt, Au, Ru, Ir, Ag, and Rh have been considered the most efficient electrocatalysts for electrochemical NRR process. [249][250][251] In addition to these noble metal catalysts, other early and late transition metals (e.g., Co, Ni, Pd, Cu, Fe, Mn, Cr) based materials have been widely studied and are some of the most popular catalysts for electrocatalytic NH 3 synthesis owing to their high catalytic activity (Figure 7c,d). [252] However, these noble and transition metals-based catalysts suffer from high cost and scarcity, while also their operational stabilities are still very questionable.…”

Pd/PdO Electrocatalysts Boost Their Intrinsic Nitrogen Reduction Reaction Activity and Selectivity via Controllably Modulating the Oxygen Level

“…The electrocatalytic nitrogen reduction reaction (eNRR) is a green and environmentally friendly approach that synthesizes ammonia (NH 3 ) from air and water with renewable electricity at ambient temperature and pressure. − Hence, the eNRR is considered a promising sustainable alternative to the industrial Haber–Bosch process. − Despite the considerable advances, the electrocatalysts still cannot simultaneously produce high selectivity and activity for the eNRR. In view of the poor N 2 adsorption and high activation barrier for splitting N–N triple bonds, the developed electrocatalysts exhibit a higher overpotential for the eNRR than for the hydrogen evolution reaction (HER), thus resulting in the limited selectivity and activity for the eNRR in aqueous solutions.…”

“…However, too few protons do not initiate the proton-coupled electron-involved eNRR. Apart from varying the electrolyte solutions, single metals with different structures can also function as mediators for the dilemma of selectivity and activity in the eNRR. , Theoretical calculation and experimental results suggest that single metals with a higher nitrogen adsorption ability than hydrogen exhibit a higher eNRR selectivity. ,,− However, too strong a binding to nitrogen species would be unfavorable for the subsequent desorption of certain intermediates during the eNRR, which results in poisoning of the metal catalysts. To mitigate the limitations by the scaling relations and efficiently enhance the intrinsic eNRR activity, several groups have resorted to alloy or metal/semiconductor catalysts to tune their electron density. , The produced appropriate electron density could efficiently regulate the adsorption of the catalysts toward nitrogen against hydrogen in aqueous electrolytes, thus elevating the eNRR activity and simultaneously depressing the HER.…”

Computational Study of Double Transition Metal Atom Anchored on Graphdiyne Monolayer for Nitrogen Electroreduction

“…So far, numerous homogeneous and heterogeneous catalysts have been developed and applied in the electrocatalytic nitrogen reduction reaction (NRR). [10,11] Recently, single-atom catalysts (SACs) are extensively studied and applied in various reactions, such as CO 2 reduction reaction, hydrogen evolution reaction (HER), oxygen reduction reaction (ORR) and methane activation reaction, due to their maximum atomic utilization and high selectivity. [12][13][14][15][16][17][18][19][20][21][22][23][24][25][26] In addition, an abundance of SACs has been designed and applied in NRR.…”

“…The electrocatalytic N 2 reduction to NH 3 is attracting a great of attentions under the moderate condition. So far, numerous homogeneous and heterogeneous catalysts have been developed and applied in the electrocatalytic nitrogen reduction reaction (NRR) [10,11] …”