Abstract
Nitric oxide (NO) has been implicated in a variety of physiological and pathological processes. Monitoring cellular levels of NO requires a sensor to feature adequate sensitivity, transient ...recording ability and biocompatibility. Herein we report a single-atom catalysts (SACs)-based electrochemical sensor for the detection of NO in live cellular environment. The system employs nickel single atoms anchored on N-doped hollow carbon spheres (Ni SACs/N-C) that act as an excellent catalyst for electrochemical oxidation of NO. Notably, Ni SACs/N-C shows superior electrocatalytic performance to the commonly used Ni based nanomaterials, attributing from the greatly reduced Gibbs free energy that are required for Ni SACs/N-C in activating NO oxidation. Moreover, Ni SACs-based flexible and stretchable sensor shows high biocompatibility and low nanomolar sensitivity, enabling the real-time monitoring of NO release from cells upon drug and stretch stimulation. Our results demonstrate a promising means of using SACs for electrochemical sensing applications.
Photocatalytic reduction of CO2 to value-added fuels is a promising route to reduce global warming and enhance energy supply. However, poor selectivity and low efficiency of catalysts are usually the ...limiting factor of their applicability. Herein, a photoinduction method was developed to achieve the formation of Cu single atoms on a UiO-66-NH2 support (Cu SAs/UiO-66-NH2) that could significantly boost the photoreduction of CO2 to liquid fuels. Notably, the developed Cu SAs/UiO-66-NH2 achieved the solar-driven conversion of CO2 to methanol and ethanol with an evolution rate of 5.33 and 4.22 μmol h–1 g–1, respectively. These yields were much higher than those of pristine UiO-66-NH2 and Cu nanoparticles/UiO-66-NH2 composites. Theoretical calculations revealed that the introduction of the Cu SAs on the UiO-66-NH2 greatly facilitates the conversion of CO2 to CHO* and CO* intermediates, leading to excellent selectivity toward methanol and ethanol. This study provides new insights for designing high-performance catalyst for photocatalytic reduction of CO2 at the atomic scale.
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•The up-to-date reports with respect to the chemical synthesis of SAA are overviewed.•The significance of SAA for representative electrochemical and heterogeneous catalytic reactions ...is analyzed.•The major challenges and opportunities pertaining to this cutting-edge field are suggested.
The development of low-cost, high-performance catalysts at the atomic level has become a challenging issue for large-scale applications of renewable clean energy technologies. Atomic sites catalysts, such as single atoms catalysts (SAC), single clusters catalysts (SCC), single-atom alloys (SAA), have proved their performance in various catalytic reactions due to their extremely high atom utilization efficiency, unique structure, and exceptional catalytic selectivity. A deep understanding and design of the active center of the catalyst at the atomic level has become a top priority for current research. Compared with SAC and SCC, SAA has its own uniqueness. In this review, we focused on the recent progress on the preparation methods of SAA and discussed the key factors controlling the structure of SAA. In addition, several important catalytic reactions performed over well-defined SAA are analyzed. Finally, the challenges and the perspectives of this cutting-edge field are suggested. We believe that this critical review provides a guidance for the rational design of SAA for catalytic applications.
The demand for high-performance non-precious-metal electrocatalysts to replace the noble metal-based catalysts for oxygen reduction reaction (ORR) is intensively increasing. Herein, single-atomic ...copper sites supported on N-doped three-dimensional hierarchically porous carbon catalyst (Cu
1
/NC) was prepared by coordination pyrolysis strategy. Remarkably, the Cu
1
/NC-900 catalyst not only exhibits excellent ORR performance with a half-wave potential of 0.894 V (vs. RHE) in alkaline media, outperforming those of commercial Pt/C (0.851 V) and Cu nanoparticles anchored on N-doped porous carbon (CuNPs/NC-900), but also demonstrates high stability and methanol tolerance. Moreover, the Cu
1
/NC-900 based Zn-air battery exhibits higher power density, rechargeability and cyclic stability than the one based on Pt/C. Both experimental and theoretical investigations demonstrated that the excellent performance of the as-obtained Cui/NC-900 could be attributed to the synergistic effect between copper coordinated by three N atoms active sites and the neighbouring carbon defect, resulting in elevated Cu d-band centers of Cu atoms and facilitating intermediate desorption for ORR process. This study may lead towards the development of highly efficient non-noble metal catalysts for applications in electrochemical energy conversion.
Designing highly active and robust platinum-free catalysts for hydrogen evolution reaction is of vital importance for clean energy applications yet challenging. Here we report highly active and ...stable cobalt-substituted ruthenium nanosheets for hydrogen evolution, in which cobalt atoms are isolated in ruthenium lattice as revealed by aberration-corrected high-resolution transmission electron microscopy and X-ray absorption fine structure measurement. Impressively, the cobalt-substituted ruthenium nanosheets only need an extremely low overpotential of 13 mV to achieve a current density of 10 mA cm
in 1 M KOH media and an ultralow Tafel slope of 29 mV dec
, which exhibit top-level catalytic activity among all reported platinum-free electrocatalysts. The theoretical calculations reveal that the energy barrier of water dissociation can greatly reduce after single cobalt atom substitution, leading to its superior hydrogen evolution performance. This study provides a new insight into the development of highly efficient platinum-free hydrogen evolution catalysts.
Three-Dimensional (3D) porous graphene, a kind of carbon material with in-plane nanopores and hierarchical pores formed between graphene layers, have attracted tremendous interests in application of ...supercapacitors due to their large specific surface areas, superior conductivity, unique porous structures and diversified compositions. Combining the advantages from both porous materials and graphene, 3D porous graphene has been regarded as an idea scaffold to build hierarchical hybrid with comprehensive electrochemical energy storage performance by introducing other substances. In this review, we aim to summarize the recent advances in fabricating 3D pure self-supported graphene-based porous structures with micro-, meso-, and macro-porous features and investigate the structure–property relationships, and their application in supercapacitors are also discussed.
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•Summarizing recent advances in fabricating 3D pure self-supported graphene-based porous structures.•Discussing the advantages of 3D porous graphene-based hybrid from both porous materials and graphene.•Investigate the structure–property relationships and their application in supercapacitors.•Figuring out the trouble and found the way for the development of 3D porous graphene-based hybrid.
The electrochemical CO2 reduction reaction (CO2RR) is of importance for reducing global CO2 emissions. Herein, we reported a highly active CO2RR catalyst, namely Co–N–Ni/NPCNSs, which is considered ...as an advanced single-site catalyst with Co–N–Ni bimetallic sites connected by a N bridge between Co and Ni. The N-bridged Co–N–Ni bimetallic sites were confirmed by the X-ray absorption spectroscopy. The Co–N–Ni/NPCNSs catalyst shows a higher turnover frequency of 2049 h−1 at a low overpotential of 370 mV and CO faradaic efficiency of 96.4% compared to that of Co–N/NPCNSs (1205 h−1 and 61.5%) and Ni–N/NPCNSs (404 h−1 and 45.0%) with single Co–N4 and Ni–N4 sites, respectively. In situ synchrotron radiation Fourier transform infrared spectra and DFT calculations show that N-bridged Co–N–Ni bimetallic sites promote the formation of COOH* intermediates, thus accelerating CO2RR.
Tungsten‐based catalysts are promising candidates to generate hydrogen effectively. In this work, a single‐W‐atom catalyst supported on metal–organic framework (MOF)‐derived N‐doped carbon (W‐SAC) ...for efficient electrochemical hydrogen evolution reaction (HER), with high activity and excellent stability is reported. High‐angle annular dark‐field scanning transmission electron microscopy (HAADF‐STEM) and X‐ray absorption fine structure (XAFS) spectroscopy analysis indicate the atomic dispersion of the W species, and reveal that the W1N1C3 moiety may be the favored local structure for the W species. The W‐SAC exhibits a low overpotential of 85 mV at a current density of 10 mA cm−2 and a small Tafel slope of 53 mV dec−1, in 0.1 m KOH solution. The HER activity of the W‐SAC is almost equal to that of commercial Pt/C. Density functional theory (DFT) calculation suggests that the unique structure of the W1N1C3 moiety plays an important role in enhancing the HER performance. This work gives new insights into the investigation of efficient and practical W‐based HER catalysts.
A single‐tungsten‐atom catalyst supported on metal–organic framework‐derived N‐doped carbon is reported. The catalyst demonstrates a high activity and excellent stability for efficient electrochemical hydrogen evolution.
Tuning the selectivity of metal catalysts is of paramount importance yet a great challenge. A new strategy to effectively control the selectivity of metal catalysts, by tuning the lattice strain, is ...reported. A certain amount of Co atoms is introduced into Ru catalysts to compress the Ru lattice, as confirmed by aberration‐corrected high‐resolution transmission electron microscopy (HRTEM) and X‐ray absorption fine structure (XAFS) measurements. We discover that the lattice strain of Ru catalysts can greatly affect their selectivity, and Ru with 3 % lattice compression exhibits extremely high catalytic selectivity for hydrogenation of 4‐nitrostyrene to 4‐aminostyrene compared to pristine Ru (99 % vs. 66 %). Theoretical studies confirm that the optimized lateral compressive strain facilitates hydrogenation of the nitro group but impedes the hydrogenation of the vinyl group. This study provides a new guideline for designing metal catalysts with high selectivity.
Taking the strain: Introducing Co atoms into a Ru catalyst compressed the Ru lattice strain, thus further affecting catalytic selectivity for hydrogenation of 4‐nitrostyrene to 4‐aminostyrene. Theoretical studies reveal that the optimized lateral compressive strain facilitates hydrogenation of the nitro group but impedes the hydrogenation of the vinyl group.
A main obstacle in the rational development of heterogeneous catalysts is the difficulty in identifying active sites. Here we show metal/oxide interfacial sites are highly active for the oxidation of ...benzyl alcohol and other industrially important primary alcohols on a range of metals and oxides combinations. Scanning tunnelling microscopy together with density functional theory calculations on FeO/Pt(111) reveals that benzyl alcohol enriches preferentially at the oxygen-terminated FeO/Pt(111) interface and undergoes readily O-H and C-H dissociations with the aid of interfacial oxygen, which is also validated in the model study of Cu
O/Ag(111). We demonstrate that the interfacial effects are independent of metal or oxide sizes and the way by which the interfaces were constructed. It inspires us to inversely support nano-oxides on micro-metals to make the structure more stable against sintering while the number of active sites is not sacrificed. The catalyst lifetime, by taking the inverse design, is thereby significantly prolonged.
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