NH 3 synthesis by the electrocatalytic N 2 reduction reaction (NRR) under ambient conditions is an appealing alternative to the currently employed industrial method-the Haber-Boschp rocess-that requires high temperature and pressure.W er eport single Mo atoms anchored to nitrogendoped porous carbon as ac ost-effective catalyst for the NRR. Benefiting from the optimally high density of active sites and hierarchically porous carbon frameworks,t his catalyst achieves ah igh NH 3 yield rate (34.0 AE 3.6 mg NH 3 h À1 mg cat. À1 )a nd ahigh Faradaic efficiency (14.6 AE 1.6 %) in 0.1m KOHatroom temperature.T hese values are considerably higher compared to previously reported non-precious-metal electrocatalysts. Moreover,t his catalyst displays no obvious current drop during a5 0000 sN RR, and high activity and durability are achieved in 0.1m HCl. The findings provideapromising lead for the design of efficient and robust single-atom non-preciousmetal catalysts for the electrocatalytic NRR.

In situtransformation of Pd into β-PdH is the origin of the high selectivity for CO in the electrochemical CO2reduction reaction using Pd as the electrocatalyst.

The development of highly active and durable catalysts for electrochemical reduction of CO2 (ERC) to CH4 in aqueous media is an efficient and environmentally friendly solution to address global problems in energy and sustainability. In this work, an electrocatalyst consisting of single Zn atoms supported on microporous N-doped carbon was designed to enable multielectron transfer for catalyzing ERC to CH4 in 1 M KHCO3 solution. This catalyst exhibits a high Faradaic efficiency (FE) of 85%, a partial current density of −31.8 mA cm–2 at a potential of −1.8 V versus saturated calomel electrode, and remarkable stability, with neither an obvious current drop nor large FE fluctuation observed during 35 h of ERC, indicating a far superior performance than that of dominant Cu-based catalysts for ERC to CH4. Theoretical calculations reveal that single Zn atoms largely block CO generation and instead facilitate the production of CH4.

Understanding the roles of metals and atomic structures in activating various elementary steps of electrocatalytic reactions can help rational design of binary or ternary catalysts for promoting activity toward desirable products via favorable pathways. Here we report on a newly developed ternary Au@PtIr core−shell catalyst for ethanol oxidation reaction (EOR) in alkaline solutions, which exhibits an activity enhancement of 6 orders of magnitude compared to AuPtIr alloy catalysts. Analysis of in situ infrared reflection absorption spectra for Au@PtIr and its bimetallic subsets, Au@Pt and PtIr alloy, found that monatomic steps and Au-induced tensile strain on PtIr facilitate C−C bond splitting via ethanol dissociative adsorption and Ir promotes dehydrogenation at low potentials. As evidenced by the CO band being observed only for the PtIr alloy that is rather inactive for ethanol dissociative adsorption, we propose that splitting the C−C bond at the earliest stage of EOR activates a direct 12-electron full oxidation pathway because hydrogen-rich fragments can be fully oxidized without CO as a poisoning intermediate. The resulting synergy of complementary effects of Au core and surface Ir leads to an outstanding performance of Au@PtIr for EOR as characterized by a low onset potential of 0.3 V and 8.3 A mg −1 all-metals peak current with 57% currents generated via full ethanol oxidation.

Ethanol is a green, sustainable, and high-energy-density liquid fuel that holds great promise for direct liquid fuel cells (DLFCs). However, it remains highly challenging to develop electrocatalysts that selectively promote the C–C bond scission for the ethanol oxidation reaction (EOR). Here, we report the facile synthesis of PtIr alloy core–shell nanocubes (NCs) with Ir-rich shells as effective EOR electrocatalysts. We find that (100)-exposed Pt38Ir NCs with one-atom-thick Ir-rich skin exhibit unprecedented EOR activity, high CO2 selectivity, and long-term stability, while pure Pt NCs and Pt17Ir NCs (two-atom thick Ir-rich skin) show less activity and lower CO2 selectivity. We demonstrate that the Pt38Ir NCs electrocatalyst can deliver a current density up to 4.5 times higher than that of Pt/C with a lower EOR onset potential by 320 mV. Its CO2 current density at 0.85 V is 14 times higher than that of commercial Pt/C. We show that the enhanced EOR activity is mainly due to the Ir-rich PtIr(100) facet that not only favors the splitting of the C–C bond by strongly adsorbing the *C x H y O/C x H y species but also promotes the desorption of CO from the PtIr surface. This work highlights the critical role of surface atom layers on shape-engineered catalysts and demonstrates a strategy for the design of efficient EOR electrocatalysts.

CoreÀshell nanoparticulate catalysts with a nonprecious metal core and a thin precious metal shell not only save precious metals but also could enhance the catalytic performance of precious metals through properly tuned strain and ligand effects. In this study, we show that, in addition to the nature and composition of core metals, the electrocatalytic properties of the precious metal shell can be tuned by varying its surface coverage. Carbon-supported NiÀPt coreÀshell nanoparticle catalysts (NiÀPt/C) with a series of Pt coverages are synthesized by depositing different amounts of Pt on Ni nanoparticles ca. 5 nm in size. It is found that Pt approximately forms an extended layer on Ni particles as its coverage does not exceed that required for a monolayer formation. The electrocatalytic properties of the NiÀPt/C catalysts, such as the stripping potential for the oxygenated adsorbates, the activity for the oxygen reduction reaction (OPR), and the electrochemical stability under continuous potential cycling, exhibit a volcano type of dependence on Pt coverage, with the apex occurring near the monolayer. This suggests that coreÀshell nanoparticles with a monolayer Pt shell would be active and durable catalysts for the ORR and that extra Pt benefits neither the ORR activity nor the durability of the coreÀshell structured electrocatalysts.

For the electrochemical hydrogen evolution reaction (HER), the electrical properties of catalysts can play an important role in influencing the overall catalytic activity. This is particularly important for semiconducting HER catalysts such as MoS , which has been extensively studied over the last decade. Herein, on-chip microreactors on two model catalysts, semiconducting MoS and semimetallic WTe , are employed to extract the effects of individual factors and study their relations with the HER catalytic activity. It is shown that electron injection at the catalyst/current collector interface and intralayer and interlayer charge transport within the catalyst can be more important than thermodynamic energy considerations. For WTe , the site-dependent activities and the relations of the pure thermodynamics to the overall activity are measured and established, as the microreactors allow precise measurements of the type and area of the catalytic sites. The approach presents opportunities to study electrochemical reactions systematically to help establish rational design principles for future electrocatalysts.

NH3 synthesis by the electrocatalytic N2 reduction reaction (NRR) under ambient conditions is an appealing alternative to the currently employed industrial method—the Haber–Bosch process—that requires high temperature and pressure. We report single Mo atoms anchored to nitrogen‐doped porous carbon as a cost‐effective catalyst for the NRR. Benefiting from the optimally high density of active sites and hierarchically porous carbon frameworks, this catalyst achieves a high NH3 yield rate (34.0±3.6 μgNH3  h−1 mgcat.−1) and a high Faradaic efficiency (14.6±1.6 %) in 0.1 m KOH at room temperature. These values are considerably higher compared to previously reported non‐precious‐metal electrocatalysts. Moreover, this catalyst displays no obvious current drop during a 50 000 s NRR, and high activity and durability are achieved in 0.1 m HCl. The findings provide a promising lead for the design of efficient and robust single‐atom non‐precious‐metal catalysts for the electrocatalytic NRR.