Construction of Dual-Atom Fe via Face-to-Face Assembly of Molecular Phthalocyanine for Superior Oxygen Reduction Reaction

Porphyry-type aromatic macrocycles such as metallo-phthalocyanines and metallo-porphyrins as single-atomic-site catalysts usually have good catalytic oxygen reduction reaction (ORR) performance. However, the construction of dual active sites using these molecules and the interaction between the active sites have not been much explored. Herein, we developed a facile approach to construct the dual-atom Fe by organizing the face-to-face self-assembly of molecular iron phthalocyanine (FePc) and transforming it into nanorod-like architectures under microwave irradiation. The (001)-oriented growth induced by strong intermolecular π–π-stacking to frame the stable-phase FePc was observed in the self-assembled FePc nanorods. The nanorods exhibited superior ORR performance than molecular FePc and state-of-the-art 20% Pt/C in alkaline media (260 and 60 mV positive shifting in half-wave potential compared with the molecular FePc/C and 20% Pt/C). Theoretical studies on crystal structures and reaction mechanisms revealed that the self-tailored space (4.92) between two neighboring Fe active sites facilitated mutual coordination with dioxygen by forming a dual-atom Fe species of a trans-bridged peroxo adduct (Fe–O–O–Fe), which favored the cleavage of the O–O bond and the release of OH* intermediates, resulting in an increase in ORR activity. This investigation revealed the possibility of enhancing the electrocatalysts’ performances by assembly and tailoring of the active sites’ interactions

Integrated Biochip–Electronic System with Single-Atom Nanozyme for <i>in</i> <i>Vivo</i> Analysis of Nitric Oxide

Nitric oxide (NO) exhibits a crucial role in various versatile and distinct physiological functions. Hence, its real-time sensing is highly important. Herein, we developed an integrated nanoelectronic system comprising a cobalt single-atom nanozyme (Co-SAE) chip array sensor and an electronic signal processing module (INDCo‑SAE) for both in vitro and in vivo multichannel qualifying of NO in normal and tumor-bearing mice. The high atomic utilization and catalytic activity of Co-SAE endowed an ultrawide linear range for NO varying from 36 to 4.1 × 105 nM with a low detection limit of 12 nM. Combining in situ attenuated total reflectance surface enhanced infrared spectroscopy (ATR-SEIRAS) measurements and density function calculation revealed the activating mechanism of Co-SAE toward NO. The NO adsorption on an active Co atom forms *NO, followed by the reaction between *NO and OH–, which could help design relevant nanozymes. Further, we investigated the NO-producing behaviors of various organs of both normal and tumor-bearing mice using the proposed device. We also evaluated the NO yield produced by the wounded mouse using the designed device and found it to be approximately 15 times that of the normal mouse. This study bridges the technical gap between a biosensor and an integrated system for molecular analysis in vitro and in vivo. The as-fabricated integrated wireless nanoelectronic system with multiple test channels significantly improved the detection efficiency, which can be widely used in designing other portable sensing devices with multiplexed analysis capability

Integrated Biochip–Electronic System with Single-Atom Nanozyme for <i>in</i> <i>Vivo</i> Analysis of Nitric Oxide

Nitric oxide (NO) exhibits a crucial role in various versatile and distinct physiological functions. Hence, its real-time sensing is highly important. Herein, we developed an integrated nanoelectronic system comprising a cobalt single-atom nanozyme (Co-SAE) chip array sensor and an electronic signal processing module (INDCo‑SAE) for both in vitro and in vivo multichannel qualifying of NO in normal and tumor-bearing mice. The high atomic utilization and catalytic activity of Co-SAE endowed an ultrawide linear range for NO varying from 36 to 4.1 × 105 nM with a low detection limit of 12 nM. Combining in situ attenuated total reflectance surface enhanced infrared spectroscopy (ATR-SEIRAS) measurements and density function calculation revealed the activating mechanism of Co-SAE toward NO. The NO adsorption on an active Co atom forms *NO, followed by the reaction between *NO and OH–, which could help design relevant nanozymes. Further, we investigated the NO-producing behaviors of various organs of both normal and tumor-bearing mice using the proposed device. We also evaluated the NO yield produced by the wounded mouse using the designed device and found it to be approximately 15 times that of the normal mouse. This study bridges the technical gap between a biosensor and an integrated system for molecular analysis in vitro and in vivo. The as-fabricated integrated wireless nanoelectronic system with multiple test channels significantly improved the detection efficiency, which can be widely used in designing other portable sensing devices with multiplexed analysis capability

Integrated Biochip–Electronic System with Single-Atom Nanozyme for <i>in</i> <i>Vivo</i> Analysis of Nitric Oxide

Nitric oxide (NO) exhibits a crucial role in various versatile and distinct physiological functions. Hence, its real-time sensing is highly important. Herein, we developed an integrated nanoelectronic system comprising a cobalt single-atom nanozyme (Co-SAE) chip array sensor and an electronic signal processing module (INDCo‑SAE) for both in vitro and in vivo multichannel qualifying of NO in normal and tumor-bearing mice. The high atomic utilization and catalytic activity of Co-SAE endowed an ultrawide linear range for NO varying from 36 to 4.1 × 105 nM with a low detection limit of 12 nM. Combining in situ attenuated total reflectance surface enhanced infrared spectroscopy (ATR-SEIRAS) measurements and density function calculation revealed the activating mechanism of Co-SAE toward NO. The NO adsorption on an active Co atom forms *NO, followed by the reaction between *NO and OH–, which could help design relevant nanozymes. Further, we investigated the NO-producing behaviors of various organs of both normal and tumor-bearing mice using the proposed device. We also evaluated the NO yield produced by the wounded mouse using the designed device and found it to be approximately 15 times that of the normal mouse. This study bridges the technical gap between a biosensor and an integrated system for molecular analysis in vitro and in vivo. The as-fabricated integrated wireless nanoelectronic system with multiple test channels significantly improved the detection efficiency, which can be widely used in designing other portable sensing devices with multiplexed analysis capability

Supplementary information files for Atomically dispersed Fe-N₄ modified with precisely located S for highly efficient oxygen reduction

Supplementary files for article Atomically dispersed Fe-N4 modified with precisely located S for highly efficient oxygen reduction. Immobilizing metal atoms by multiple nitrogen atoms has triggered exceptional catalytic activity toward many critical electrochemical reactions due to their merits of highly unsaturated coordination and strong metal-substrate interaction. Herein, atomically dispersed Fe-NC material with precise sulfur modification to Fe periphery (termed as Fe-NSC) was synthesized, X-ray absorption near edge structure analysis confirmed the central Fe atom being stabilized in a specific configuration of Fe(N3)(N–C–S). By enabling precisely localized S doping, the electronic structure of Fe-N4 moiety could be mediated, leading to the beneficial adjustment of absorption/desorption properties of reactant/intermediate on Fe center. Density functional theory simulation suggested that more negative charge density would be localized over Fe-N4 moiety after S doping, allowing weakened binding capability to *OH intermediates and faster charge transfer from Fe center to O species. Electrochemical measurements revealed that the Fe-NSC sample exhibited significantly enhanced oxygen reduction reaction performance compared to the S-free Fe-NC material (termed as Fe-NC), showing an excellent onset potential of 1.09 V and half-wave potential of 0.92 V in 0.1 M KOH. Our work may enlighten relevant studies regarding to accessing improvement on the catalytic performance of atomically dispersed M-NC materials by managing precisely tuned local environments of M-Nx moiety

Atomically dispersed Fe-N₄ modified with precisely located S for highly efficient oxygen reduction

Immobilizing metal atoms by multiple nitrogen atoms has triggered exceptional catalytic activity toward many critical electrochemical reactions due to their merits of highly unsaturated coordination and strong metal-substrate interaction. Herein, atomically dispersed Fe-NC material with precise sulfur modification to Fe periphery (termed as Fe-NSC) was synthesized, X-ray absorption near edge structure analysis confirmed the central Fe atom being stabilized in a specific configuration of Fe(N3)(N–C–S). By enabling precisely localized S doping, the electronic structure of Fe-N4 moiety could be mediated, leading to the beneficial adjustment of absorption/desorption properties of reactant/intermediate on Fe center. Density functional theory simulation suggested that more negative charge density would be localized over Fe-N4 moiety after S doping, allowing weakened binding capability to *OH intermediates and faster charge transfer from Fe center to O species. Electrochemical measurements revealed that the Fe-NSC sample exhibited significantly enhanced oxygen reduction reaction performance compared to the S-free Fe-NC material (termed as Fe-NC), showing an excellent onset potential of 1.09 V and half-wave potential of 0.92 V in 0.1 M KOH. Our work may enlighten relevant studies regarding to accessing improvement on the catalytic performance of atomically dispersed M-NC materials by managing precisely tuned local environments of M-Nx moiety

Engineering Interfacial Aerophilicity of Nickel-Embedded Nitrogen-Doped CNTs for Electrochemical CO₂ Reduction

Electrochemical CO2 reduction reaction (CO2RR) is a promising approach for conversion of CO2 to value-added chemicals. In this contribution, we demonstrated an electrode design strategy via wettability control and fabricated a freestanding three-dimensional electrode. This electrode design strategy created more three-phase (solid–liquid–gas) contacts due to the sufficient amount of CO2 gas bubbles attached to the surface of the electrode under catalytic turnover conditions and the ongoing change of electrolyte wetting, and replacement of electrolyte by the gas bubble promotes the activity of CO2RR. This work exploits a new way that sheds light on electrode design for underwater gas-consumption electrocatalytic applications

Engineering Interfacial Aerophilicity of Nickel-Embedded Nitrogen-Doped CNTs for Electrochemical CO₂ Reduction

Electrochemical CO2 reduction reaction (CO2RR) is a promising approach for conversion of CO2 to value-added chemicals. In this contribution, we demonstrated an electrode design strategy via wettability control and fabricated a freestanding three-dimensional electrode. This electrode design strategy created more three-phase (solid–liquid–gas) contacts due to the sufficient amount of CO2 gas bubbles attached to the surface of the electrode under catalytic turnover conditions and the ongoing change of electrolyte wetting, and replacement of electrolyte by the gas bubble promotes the activity of CO2RR. This work exploits a new way that sheds light on electrode design for underwater gas-consumption electrocatalytic applications

Engineering Interfacial Aerophilicity of Nickel-Embedded Nitrogen-Doped CNTs for Electrochemical CO₂ Reduction

Electrochemical CO2 reduction reaction (CO2RR) is a promising approach for conversion of CO2 to value-added chemicals. In this contribution, we demonstrated an electrode design strategy via wettability control and fabricated a freestanding three-dimensional electrode. This electrode design strategy created more three-phase (solid–liquid–gas) contacts due to the sufficient amount of CO2 gas bubbles attached to the surface of the electrode under catalytic turnover conditions and the ongoing change of electrolyte wetting, and replacement of electrolyte by the gas bubble promotes the activity of CO2RR. This work exploits a new way that sheds light on electrode design for underwater gas-consumption electrocatalytic applications

Enhancing Selective Electrochemical CO₂ Reduction by In Situ Constructing Tensile-Strained Cu Catalysts

Heteroatom-doped Cu-based catalysts have been found to show not only enhanced activity of electrochemical CO2 reduction reaction (CO2RR) but also the possibility to tune the selectivity of CO2RR. However, the complex and variable nature of Cu-based materials renders it difficult to elucidate the origin of the improved performance, which further hinders the rational design of catalysts. Here, we demonstrate that the activity and selectivity of CO2RR can be tuned by manipulating the lattice strain of Cu-based catalysts. The combined operando and ex situ spectroscopic characterizations reveal that the initial compressively strained Sn-doped CuO catalysts could be converted to tensile-strained Sn/Cu alloy catalysts under reaction conditions. In situ attenuated total reflectance surface-enhanced infrared absorption spectroscopy (ATR-SEITAS) and theoretical calculations further show that the tensile-strained Sn/Cu alloy catalysts favor CO formation due to the preponderant adsorption of *CO and much lower adsorption free energies of *COOH, thus effectively suppressing the dimerization process and the production of HCOOH and H2. This work provides a strategy to tune the CO2RR performance of Cu-based catalysts by manipulating the lattice strain