Ample Lewis Acidic Sites in Mg₂B₂O₅ Facilitate N₂ Electroreduction through Bonding–Antibonding Interactions

Abstract

Extensive research on the electrochemical nitrogen reduction reaction (NRR) has put forward a sound list of potential catalyst materials with properties inducing N2 adsorption, protonation, and reduction. However, rather than a random selection of catalysts, it is essential to understand the vitals in terms of orbital orientation and charge distribution that actually manipulate the rate-determining steps of NRR. Realizing these factors, herein we have explored a main group earth-abundant Mg-based electrocatalyst Mg2B2O5 for NRR due to the abundance of Lewis acid sites in the catalyst favoring the bonding–antibonding interactions with the N2 molecules. Positron annihilation studies indicate that the electronic charge distribution within the catalyst has shallow surface oxygen vacancies. These features in the catalyst enabled a sound Faradaic efficiency of 46.4% at −0.1 V vs reversible hydrogen electrode for the selective NH3 production in neutral electrolyte. In situ Fourier transform infrared suggests a maximum N–N bond polarization at −0.1 V and detected H–N–H and –NH2 intermediates during the course of the NRR on the catalyst surface. In a broader picture, the biocompatibility of Mg2+ diversifies the utility of this catalyst material in N2/biofuel cell applications that would certainly offer a green alternative toward our goal of a sustainable society.

p-Block Metal Oxide as an Efficient Electrocatalyst for Boosting Ambient Ammonia Synthesis

“…Then, their linear regression plots were made between the scan rate and Δ j (difference of anodic and cathodic current densities) obtained from the cyclic voltammetry (CV) curves to get a straight line by fitting with slope, giving rise to the double-layer capacitance ( C dl ) value, as shown in Figure c. Next, electrochemically active surface area (ECSA) was calculated using eq S2 in the SI, and it was found that ECSA in the case of the N 2 medium was less as compared to in the Ar medium presented by the bar plot in Figure d. This result suggested that more active sites were occupied with N 2 on ZAO, leading to lower ECSA in N 2 as compared to Ar.…”

Improved catalytic activity on transitioning from inverse to normal spinel in Zn2−xGa2xSn1−xO4: a robust bifunctional OER and HER electrocatalyst

“…Due to the fossil fuel depletion as well as the environmental pollution it is inevitable to search for alternative renewable energy sources. 1,2 Hydrogen production from water splitting is a clean and sustainable approach for solving the problem. [2][3][4][5] Electrochemical water splitting is one of the most efficient ways for hydrogen production for the sustainable energy.…”