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Abstract Strain engineering is an effective strategy in modulating activity of electrocatalysts, but the effect of strain on electrochemical stability of catalysts remains poorly understood. In this work, we combineab initiothermodynamics and molecular dynamics simulations to examine the role of compressive and tensile strain in the interplay between activity and stability of metal oxides considering RuOand IrOas exemplary catalysts. We reveal that although compressive strain leads to improved activity via the adsorbate‐evolving mechanism of the oxygen evolution reaction, even small strains should substantially destabilize these catalysts promoting dissolution of transition metals. In contrast, our results show that the metal oxides requiring tensile strain to promote their catalytic activity may also benefit from enhanced stability. Importantly, we also find that the detrimental effect of strain on electrochemical stability of atomically flat surfaces could be even greater than that of surface defects. 

Abstract A direct electrosynthesis of H₂O₂from either O₂or H₂O is an attractive strategy to replace the energy‐intensive industrial anthraquinone process. Two‐electron water oxidation reaction (2e‐WOR) offers several advantages over the oxygen reduction reaction such as better mass transfer due to the absence of gas‐phase reactants. However, 2e‐WOR is a more challenging and less studied process with only a handful of metal oxides exhibiting reasonable activity/selectivity properties. Herein, we employ density‐functional‐theory calculations to screen a variety of metal‐nitrogen‐graphene structures for 2e‐WOR. As a consequence of scaling between the adsorption energies of reaction intermediates, we determine a linear relation between selectivities for the first and second reaction steps of 2e‐WOR, viz. that if selectivity toward adsorbed OH is improved, then selectivity toward H₂O₂at the subsequent step is decreased. We also find that selectivity and activity are linearly scaled in such a way that a higher activity (i. e., a lower overpotential) leads to a lower selectivity for the H₂O₂formation step. Based on the obtained results several chemistries, e. g., containing NiN_x−C moieties, are predicted to rival the best‐performing metal oxides such as ZnO and CaSnO₃in terms of combination of their activity/selectivity characteristics for 2e‐WOR. 

Abstract Based on the coincident onsets of oxygen evolution reaction (OER) and metal dissolution for many metal‐oxide catalysts it was suggested that OER triggers dissolution. It is believed that both processes share common intermediates, yet exact mechanistic details remain largely unknown. For example, there is still no clear understanding as to why rutile IrO₂exhibits such an exquisite stability among water‐splitting electrocatalysts. Here, we employ density functional theory calculations to analyze interactions between water and the (110) surface of rutile RuO₂and IrO₂as a response to oxygen evolution involving lattice oxygen species. We observe that these oxides display qualitatively different interfacial behavior that should have important implications for their electrochemical stability. Specifically, it is found that IrO₂(110) becomes further stabilized under OER conditions due to the tendency to form highly stable low oxidation state Ir(III) species. In contrast, Ru species at RuO₂(110) are prone to facile reoxidation by solution water. This should facilitate the formation of high Ru oxidation state intermediates (>IV) accelerating surface restructuring and metal dissolution. 

Abstract Extensive research efforts are currently dedicated to the search for new electrocatalyst materials in which expensive and rare noble metals are replaced with cheaper and more abundant transition metals. Recently, numerous alloys, oxides, and composites with such metals have been identified as highly active electrocatalysts through the use of high‐throughput screening methods with the help of activity descriptors. Up to this point, stability has lacked such descriptors. Hence, we elucidate the role of intrinsic metal/oxide properties on the corrosion behavior of representative 3d, 4d, and 5d transition metals. Electrochemical dissolution of nine transition metals is quantified using online inductively coupled plasma mass spectrometry (ICP‐MS). Based on the obtained dissolution data in alkaline and acidic media, we establish clear periodic correlations between the amount of dissolved metal, the cohesive energy of the metal atoms (E_coh), and the energy of oxygen adsorption on the metal (ΔH_O,ads). Such correlations can support the knowledge‐driven search for more stable electrocatalysts. 

Abstract Nitrate is a ubiquitous aqueous pollutant from agricultural and industrial activities. At the same time, conversion of nitrate to ammonia provides an attractive solution for the coupled environmental and energy challenge underlying the nitrogen cycle, by valorizing a pollutant to a carbon-free energy carrier and essential chemical feedstock. Mass transport limitations are a key obstacle to the efficient conversion of nitrate to ammonia from water streams, due to the dilute concentration of nitrate. Here, we develop bifunctional electrodes that couple a nitrate-selective redox-electrosorbent (polyaniline) with an electrocatalyst (cobalt oxide) for nitrate to ammonium conversion. We demonstrate the synergistic reactive separation of nitrate through solely electrochemical control. Electrochemically-reversible nitrate uptake greater than 70 mg/g can be achieved, with electronic structure calculations and spectroscopic measurements providing insight into the underlying role of hydrogen bonding for nitrate selectivity. Using agricultural tile drainage water containing dilute nitrate (0.27 mM), we demonstrate that the bifunctional electrode can achieve a 8-fold up-concentration of nitrate, a 24-fold enhancement of ammonium production rate (108.1 ug h −1  cm −2 ), and a >10-fold enhancement in energy efficiency when compared to direct electrocatalysis in the dilute stream. Our study provides a generalized strategy for a fully electrified reaction-separation pathway for modular nitrate remediation and ammonia production.