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Single-atom catalysts (SACs) with high catalytic activity as well as great stability are demonstrating great promotion in electrocatalytic energy conversion, which is also a big challenge to achieve. Herein, we proposed a facile synthetic strategy to construct nickel-iron bimetallic hydroxide nanoribbon stabilized single-atom iridium catalysts (Ir-NiFe-OH), where the nickel-iron hydroxide nanoribbon not only can serve as good electronic conductor, but also can well stabilize and fully expose single-atom sites. Adopted as catalyst for urea oxidation reaction (UOR), it exhibited excellent UOR performance that it only needed a low operated potential of 1.38 V to achieve the current density of 100 mA·cm−2. In-situ Fourier transform infrared spectroscopy, X-ray absorption spectrum, and density functional theory calculations proved that Ir species are active centers and the existence of both Ni and Fe in the local structure of Ir atom can optimize the d-band center of Ir species, promoting the adsorption of intermediates and desorption of products for UOR. The hydrogen evolution reaction (HER)/UOR electrocatalytic cell demanded voltages of 1.46 and 1.50 V to achieve 50 and 100 mA·cm−2, respectively, which demonstrated a higher activity and better stability than those of conventional catalysts. This work opens a new avenue to develop catalysts for UORs with boosted activity and stability. [ABSTRACT FROM AUTHOR]

Electrocatalytic acetylene semi-hydrogenation to ethylene powered by renewable electricity represents a sustainable pathway, but the inadequate current density and single-pass yield greatly impedes the production efficiency and industrial application. Herein, we develop a F-modified Cu catalyst that shows an industrial partial current density up to 0.76 A cm−2 with an ethylene Faradic efficiency surpass 90%, and the maximum single-pass yield reaches a notable 78.5%. Furthermore, the Cu-F showcase the capability to directly convert acetylene into polymer-grade ethylene in a tandem flow cell, almost no acetylene residual in the production. Combined characterizations and calculations reveal that the Cuδ+ (near fluorine) enhances the water dissociation, and the generated active hydrogen are immediately transferred to Cu0 (away from fluorine) and react with the locally adsorbed acetylene. Therefore, the hydrogen evolution reaction is surpassed and the overall acetylene semi-hydrogenation performance is boosted. Our findings provide new opportunity towards rational design of catalysts for large-scale electrosynthesis of ethylene and other important industrial raw. Efficient electroreduction of acetylene to ethylene is crucial for industrial applications. Here, the authors reported fluorine modified copper for direct conversion of acetylene to polymer-grade ethylene in one single-pass with industrial-current-density. [ABSTRACT FROM AUTHOR]

Highlights: Oxygen-coordinated single-atom Mn catalyst was fabricated via introducing oxygen functional groups rich bacterial cellulose as the adsorption regulator through a combined impregnation–pyrolysis–etching synthetic route. Mn–O–C as the electrocatalyst exhibits superior electrocatalytic activity toward ammonia synthesis with a maximum NH3 yield rate of 1476.9 ± 62.6 μg h−1 cm−2 at − 0.7 V (vs. RHE) and a faradaic efficiency of 89.0 ± 3.8% at − 0.5 V (vs. RHE) under ambient conditions. Electrocatalytic mechanism of Mn–(O–C2)4 site for nitrate reduction reaction is unveiled by a combination of in situ spectroscopy characterization and computational study. Electrocatalytic nitrate reduction reaction has attracted increasing attention due to its goal of low carbon emission and environmental protection. Here, we report an efficient NitRR catalyst composed of single Mn sites with atomically dispersed oxygen (O) coordination on bacterial cellulose-converted graphitic carbon (Mn–O–C). Evidence of the atomically dispersed Mn–(O–C2)4 moieties embedding in the exposed basal plane of carbon surface is confirmed by X-ray absorption spectroscopy. As a result, the as-synthesized Mn–O–C catalyst exhibits superior NitRR activity with an NH3 yield rate (RNH3) of 1476.9 ± 62.6 μg h−1 cm−2 at − 0.7 V (vs. reversible hydrogen electrode, RHE) and a faradaic efficiency (FE) of 89.0 ± 3.8% at − 0.5 V (vs. RHE) under ambient conditions. Further, when evaluated with a practical flow cell, Mn–O–C shows a high RNH3 of 3706.7 ± 552.0 μg h−1 cm−2 at a current density of 100 mA cm−2, 2.5 times of that in the H cell. The in situ FT-IR and Raman spectroscopic studies combined with theoretical calculations indicate that the Mn–(O–C2)4 sites not only effectively inhibit the competitive hydrogen evolution reaction, but also greatly promote the adsorption and activation of nitrate (NO3−), thus boosting both the FE and selectivity of NH3 over Mn–(O–C2)4 sites. [ABSTRACT FROM AUTHOR]

Uncovering the dynamics of active sites in the working conditions is crucial to realizing increased activity, enhanced stability and reduced cost of oxygen evolution reaction (OER) electrocatalysts in proton exchange membrane electrolytes. Herein, we identify at the atomic level potential-driven dynamic-coupling oxygen on atomically dispersed hetero-nitrogen-configured Ir sites (AD-HN-Ir) in the OER working conditions to successfully provide the atomically dispersed Ir electrocatalyst with ultrahigh electrochemical acidic OER activity. Using in-situ synchrotron radiation infrared and X-ray absorption spectroscopies, we directly observe that one oxygen atom is formed at the Ir active site with an O-hetero-Ir-N4 structure as a more electrophilic active centre in the experiment, which effectively promotes the generation of key *OOH intermediates under working potentials; this process is favourable for the dissociation of H2O over Ir active sites and resistance to over-oxidation and dissolution of the active sites. The optimal AD-HN-Ir electrocatalyst delivers a large mass activity of 2860 A gmetal−1 and a large turnover frequency of 5110 h−1 at a low overpotential of 216 mV (10 mA cm−2), 480–510 times larger than those of the commercial IrO2. More importantly, the AD-HN-Ir electrocatalyst shows no evident deactivation after continuous 100 h OER operation in an acidic medium. Uncovering the dynamics of active sites in the working conditions is important yet challenging. Here the authors identify dynamic-coupling oxygen on atomically dispersed iridium sites during oxygen evolution reaction using in situ techniques. [ABSTRACT FROM AUTHOR]

The grand challenge in the development of atomically dispersed metallic catalysts is their low metal-atom loading density, uncontrollable localization and ambiguous interactions with supports, posing difficulty in maximizing their catalytic performance. Here, we achieve an interface catalyst consisting of atomic cobalt array covalently bound to distorted 1T MoS2 nanosheets (SA Co-D 1T MoS2). The phase of MoS2 transforming from 2H to D-1T, induced by strain from lattice mismatch and formation of Co-S covalent bond between Co and MoS2 during the assembly, is found to be essential to form the highly active single-atom array catalyst. SA Co-D 1T MoS2 achieves Pt-like activity toward HER and high long-term stability. Active-site blocking experiment together with density functional theory (DFT) calculations reveal that the superior catalytic behaviour is associated with an ensemble effect via the synergy of Co adatom and S of the D-1T MoS2 support by tuning hydrogen binding mode at the interface. While single-atom catalysis offers an efficient materials usage, the ambiguous interactions with supports poses a difficulty in understanding catalytic performances. Here, authors show an ensemble effect via synergy of Co adatoms and the S of MoS2 supports to boost hydrogen evolution activities. [ABSTRACT FROM AUTHOR]