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Maximizing the catalytic activity of single-atom catalysts is vital for the application of single-atom catalysts in industrial water-alkali electrolyzers, yet the modulation of the catalytic properties of single-atom catalysts remains challenging. Here, we construct strain-tunable sulphur vacancies around single-atom Ru sites for accelerating the alkaline hydrogen evolution reaction of single-atom Ru sites based on a nanoporous MoS 2 -based Ru single-atom catalyst. By altering the strain of this system, the synergistic effect between sulphur vacancies and Ru sites is amplified, thus changing the catalytic behavior of active sites, namely, the increased reactant density in strained sulphur vacancies and the accelerated hydrogen evolution reaction process on Ru sites. The resulting catalyst delivers an overpotential of 30 mV at a current density of 10 mA cm −2 , a Tafel slope of 31 mV dec −1 , and a long catalytic lifetime. This work provides an effective strategy to improve the activities of single-atom modified transition metal dichalcogenides catalysts by precise strain engineering. The modulation of single-atom catalyst properties for industrial applications remains challenging. Here, authors use strain engineering to amplify the synergistic effect between MoS 2 ’s sulphur vacancies and single-atom Ru sites and accelerate H 2 evolution electrocatalysis.

Iron phthalocyanine (FePc) is a promising non-precious catalyst for the oxygen reduction reaction (ORR). Unfortunately, FePc with plane-symmetric FeN 4 site usually exhibits an unsatisfactory ORR activity due to its poor O 2 adsorption and activation. Here, we report an axial Fe–O coordination induced electronic localization strategy to improve its O 2 adsorption, activation and thus the ORR performance. Theoretical calculations indicate that the Fe–O coordination evokes the electronic localization among the axial direction of O–FeN 4 sites to enhance O 2 adsorption and activation. To realize this speculation, FePc is coordinated with an oxidized carbon. Synchrotron X-ray absorption and Mössbauer spectra validate Fe–O coordination between FePc and carbon. The obtained catalyst exhibits fast kinetics for O 2 adsorption and activation with an ultralow Tafel slope of 27.5 mV dec −1 and a remarkable half-wave potential of 0.90 V. This work offers a new strategy to regulate catalytic sites for better performance. Iron phthalocyanine with a 2D structure and symmetric electron distribution around Fe-N 4 active sites is not optimal for O 2 adsorption and activation. Here, the authors report an axial Fe–O coordination induced electronic localization strategy to enhance oxygen reduction reaction performance.

Designing efficient single-atom catalysts (SACs) for oxygen evolution reaction (OER) is critical for water-splitting. However, the self-reconstruction of isolated active sites during OER not only influences the catalytic activity, but also limits the understanding of structure-property relationships. Here, we utilize a self-reconstruction strategy to prepare a SAC with isolated iridium anchored on oxyhydroxides, which exhibits high catalytic OER performance with low overpotential and small Tafel slope, superior to the IrO 2 . Operando X-ray absorption spectroscopy studies in combination with theory calculations indicate that the isolated iridium sites undergo a deprotonation process to form the multiple active sites during OER, promoting the O–O coupling. The isolated iridium sites are revealed to remain dispersed due to the support effect during OER. This work not only affords the rational design strategy of OER SACs at the atomic scale, but also provides the fundamental insights of the operando OER mechanism for highly active OER SACs. Direct observation of the atomic and electronic structure of a single-atom catalyst is essential. Here, the authors report an oxyhydroxide stabilized iridium catalyst with superior oxygen evolution catalytic activity and identify the isolated iridium sites which promote the H 2 O attack and O–O coupling.

Designing efficient electrocatalysts for hydrogen evolution reaction is significant for renewable and sustainable energy conversion. Here, we report single-atom platinum decorated nanoporous Co 0 . 85 Se (Pt/np-Co 0 . 85 Se) as efficient electrocatalysts for hydrogen evolution. The achieved Pt/np-Co 0 . 85 Se shows high catalytic performance with a near-zero onset overpotential, a low Tafel slope of 35 mV dec −1 , and a high turnover frequency of 3.93 s −1 at −100 mV in neutral media, outperforming commercial Pt/C catalyst and other reported transition-metal-based compounds. Operando X-ray absorption spectroscopy studies combined with density functional theory calculations indicate that single-atom platinum in Pt/np-Co 0 . 85 Se not only can optimize surface states of Co 0 . 85 Se active centers under realistic working conditions, but also can significantly reduce energy barriers of water dissociation and improve adsorption/desorption behavior of hydrogen, which synergistically promote thermodynamics and kinetics. This work opens up further opportunities for local electronic structures tuning of electrocatalysts to effectively manipulate its catalytic properties by an atomic-level engineering strategy. While water splitting chemistry provides a renewable means to produce carbon-neutral hydrogen fuel, the most efficient catalysts require rare and expensive platinum. Here, authors prepare single-atom platinum on cobalt selenide as a high-performance hydrogen evolution electrocatalyst.

Conversion into high-value-added organic nitrogen compounds through electrochemical C-N coupling reactions under ambient conditions is regarded as a sustainable development strategy to achieve carbon neutrality and high-value utilization of harmful substances. Herein, we report an electrochemical process for selective synthesis of high-valued formamide from carbon monoxide and nitrite with a Ru 1 Cu single-atom alloy under ambient conditions, which achieves a high formamide selectivity with Faradaic efficiency of 45.65 ± 0.76% at −0.5 V vs. RHE. In situ X-ray absorption spectroscopy, coupled with in situ Raman spectroscopy and density functional theory calculations results reveal that the adjacent Ru-Cu dual active sites can spontaneously couple *CO and *NH 2 intermediates to realize a critical C-N coupling reaction, enabling high-performance electrosynthesis of formamide. This work offers insight into the high-value formamide electrocatalysis through coupling CO and NO 2 − under ambient conditions, paving the way for the synthesis of more-sustainable and high-value chemical products. Conversion into high-value-added organic nitrogen compounds through electrochemical C-N coupling reactions is considered a sustainable strategy to achieve carbon neutrality. Herein, we report the selective electrosynthesis of formamide from carbon monoxide and nitrite using Ru 1 Cu single-atoms catalyst.

Electrocatalytic nitrite reduction to the valuable ammonia is a green and sustainable alternative to the conventional Haber-Bosch method for ammonia synthesis, while the activity and selectivity for ammonia production remains poor at low nitrite concentrations. Herein, we report a nanoporous intermetallic single-atom alloy CuZn (np/ISAA-CuZn) catalyst with completely isolated Cu-Zn active-sites, which achieves neutral nitrite reduction reaction with a remarkable NH 3 Faradaic efficiency over 95% and the highest energy efficiency of ≈ 59.1% in wide potential range from −0.2 to −0.8 V vs. RHE. The np/ISAA-CuZn electrocatalyst was able to operate stably at 500 mA cm −2 for 220 h under membrane electrode assembly conditions with a stabilized NH 3 Faraday efficiency of ~80% and high NO 2 ‒ removal rate of ~100%. A series of in situ experimental studies combined with density functional theory calculations reveal that strong electronic interactions of isolated Cu-Zn active-sites altered the protonation adsorption species, effectively alleviating the protonation barrier of *NO 2 and thus greatly facilitating the selective reduction of NO 2 − into NH 3 . Electrocatalytic nitrite reduction is a green alternative to the Haber-Bosch process, but its ammonia production remains inefficient at low nitrite levels. Here the authors report an intermetallic single atom alloy CuZn catalyst for nitrite reduction to ammonia with high efficiency and stability at low nitrite concentration of 1−10 mM.

Ruthenium dioxide is the most promising alternative to the prevailing but expensive iridium-based catalysts for the oxygen evolution reaction in proton-exchange membrane water electrolyzers. However, the under-coordinated lattice oxygen of ruthenium dioxide is prone to over-oxidation, and oxygen vacancies are formed at high oxidation potentials under acidic corrosive conditions. Consequently, ruthenium atoms adjacent to oxygen vacancies are oxidized into soluble high-valence derivatives, causing the collapse of the ruthenium dioxide crystal structure and leading to its poor stability. Here, we report an oxyanion protection strategy to prevent the formation of oxygen vacancies on the ruthenium dioxide surface by forming coordination-saturated lattice oxygen. Combining density functional theory calculations, electrochemical measurements, and a suite of operando spectroscopies, we showcase that barium-anchored sulfate can greatly impede ruthenium loss and extend the lifetime of ruthenium-based catalysts during acidic oxygen evolution, while maintaining the activity. This work paves a new way for designing stable and active anode catalysts toward acidic water splitting. Designing stable Ru-based catalysts for acidic oxygen evolution remains a challenge. Here, the authors propose an oxyanion protection strategy to prevent the formation of oxygen vacancies on the RuO 2 surface by creating coordination-saturated lattice oxygen, thereby greatly enhancing the stability.

Atomically dispersed transition metals on carbon-based aromatic substrates are an emerging class of electrocatalysts for the electroreduction of CO 2 . However, electron delocalization of the metal site with the carbon support via d-π conjugation strongly hinders CO 2 activation at the active metal centers. Herein, we introduce a strategy to attenuate the d-π conjugation at single Ni atomic sites by functionalizing the support with cyano moieties. In situ attenuated total reflection infrared spectroscopy and theoretical calculations demonstrate that this strategy increases the electron density around the metal centers and facilitates CO 2 activation. As a result, for the electroreduction of CO 2 to CO in aqueous KHCO 3 electrolyte, the cyano-modified catalyst exhibits a turnover frequency of ~22,000 per hour at −1.178 V versus the reversible hydrogen electrode (RHE) and maintains a Faradaic efficiency (FE) above 90% even with a CO 2 concentration of only 30% in an H-type cell. In a flow cell under pure CO 2 at −0.93 V versus RHE the cyano-modified catalyst enables a current density of −300 mA/cm 2 with a FE above 90%. Electroreduction of CO 2 on single atom catalysts is often hindered by electron delocalization of the metal sites. To improve CO 2 activation, here the authors functionalize the carbon support with cyano moieties, thereby attenuating metal-substrate conjugation and improving CO 2 to CO conversion.

Metal borides/borates have been considered promising as oxygen evolution reaction catalysts; however, to date, there is a dearth of evidence of long-term stability at practical current densities. Here we report a phase composition modulation approach to fabricate effective borides/borates-based catalysts. We find that metal borides in-situ formed metal borates are responsible for their high activity. This knowledge prompts us to synthesize NiFe-Boride, and to use it as a templating precursor to form an active NiFe-Borate catalyst. This boride-derived oxide catalyzes oxygen evolution with an overpotential of 167 mV at 10 mA/cm 2 in 1 M KOH electrolyte and requires a record-low overpotential of 460 mV to maintain water splitting performance for over 400 h at current density of 1 A/cm 2 . We couple the catalyst with CO reduction in an alkaline membrane electrode assembly electrolyser, reporting stable C 2 H 4 electrosynthesis at current density 200 mA/cm 2 for over 80 h. Metal borides/borates are promising candidates to become high-performance alkaline oxygen evolution reaction catalysts. This study reports an in-situ phase composition modulation approach to fabricate boride/borate-based catalysts.

Manipulation C-C coupling pathway is of great importance for selective CO 2 electroreduction but remain challenging. Herein, two model Cu-based catalysts, by modifying Cu nanowires with Ag nanoparticles (AgCu NW) and Ag single atoms (Ag 1 Cu NW), respectively, are rationally designed for exploring the C-C coupling mechanisms in electrochemical CO 2 reduction reaction (CO 2 RR). Compared to AgCu NW, the Ag 1 Cu NW exhibits a more than 10-fold increase of C 2 selectivity in CO 2 reduction to ethanol, with ethanol-to-ethylene ratio increased from 0.41 over AgCu NW to 4.26 over Ag 1 Cu NW. Via a variety of o perando /in-situ techniques and theoretical calculation, the enhanced ethanol selectivity over Ag 1 Cu NW is attributed to the promoted H 2 O dissociation over the atomically dispersed Ag sites, which effectively accelerated *CO hydrogenation to form *CHO intermediate and facilitated asymmetric *CO-*CHO coupling over paired Cu atoms adjacent to single Ag atoms. Results of this work provide deep insight into the C-C coupling pathways towards target C 2+ product and shed light on the rational design of efficient CO 2 RR catalysts with paired active sites. Manipulating the carbon-carbon coupling pathway in CO 2 electroreduction is vital yet challenging. Here, by studying two model copper-based catalysts with distinct ethylene and ethanol selectivity, authors investigate the mechanistic origins for symmetric and asymmetric carbon-carbon coupling.