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A novel F127-assisted ZIF-67 pyrolysis strategy to construct FeCo nanoalloys encapsulated in nitrogen-doped carbon for efficient oxygen reduction reaction was reported.

Formate is an important liquid chemical, which can be produced by electrocatalytic carbon dioxide reduction reaction (CO2RR). Most of the metal catalysts for CO2RR to formate are toxic or noble metals, such as Cd, Hg, Pb, Sn and Pd, leading to the environmental pollution or increased production costs. Herein, we develop an environmentally friendly and low-cost NiZn alloy catalyst for CO2RR to formate. The X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) confirm the alloy structure of the prepared NiZn catalyst. As for a catalyst for CO2RR, the NiZn alloy exhibits the FEHCOO- (Faraday efficiency of HCOO-) of 36 ± 0.7% at −0.9 V vs. RHE in 0.1 M KHCO3, and remarkable stability for 40,000 s at −0.8, −0.9, −1.0 and −1.1 V vs. RHE, respectively. Theoretical calculation results indicate that the NiZn alloy exhibits the middle valence electron structure between the Zn and Ni metal, resulting in the favorable pathway for HCOOH formation but unfavorable for the hydrogen evolution reaction and CO production. The Ultraviolet Photoelectron Spectroscopy results verify the modulated valence electron structure for NiZn alloy as compared to Ni and Zn, consistent with the theoretical calculation results. This work provides new insights into design of alloy catalysts for CO2RR to formate.

Development of high-performance and cost-effective catalysts for electrocatalytic hydrogen evolution reaction (HER) play crucial role in the growing hydrogen economy. Recently, the atomically dispersed metal catalysts have attracted increasing attention due to their ultimate atom utilization and great potential for highly cost-effective and high-efficiency HER electrocatalyst. Herein, we propose a high-temperature treatment strategy to furtherly improve the HER performance of atomically dispersed Pt-based catalyst. Interestingly, after appropriate high-temperature treatment on the atomically dispersed Pt0.8@CN, the Pt species on the designed N-doped porous carbon substrate with rich defect sites can be re-dispersed to single atom state with new coordination environment. The obtained Pt0.8@CN-1000 shows superior HER performance with overpotential of 13 mV at 10 mA cm−2 and mass activity of 11,284 mA/mgPt at −0.1 V, much higher than that of the pristine Pt0.8@CN and commercial Pt/C catalyst. The experimental and theoretical investigations indicate that the high-temperature treatment induces the restructuring of coordination environment and then the optimized Pt electronic state leads to the enhanced HER performances. This work affords new strategy and insights to develop the atomically dispersed high-efficiency catalysts.

Electrochemical production of hydrogen peroxide (H2 O2 ) through two-electron (2 e- ) oxygen reduction reaction (ORR) is an on-site and clean route. Oxygen-doped carbon materials with high ORR activity and H2 O2 selectivity have been considered as the promising catalysts, however, there is still a lack of direct experimental evidence to identify true active sites at the complex carbon surface. Herein, we propose a chemical titration strategy to decipher the oxygen-doped carbon nanosheet (OCNS900 ) catalyst for 2 e- ORR. The OCNS900 exhibits outstanding 2 e- ORR performances with onset potential of 0.825 V (vs. RHE), mass activity of 14.5 A g-1 at 0.75 V (vs. RHE) and H2 O2 production rate of 770 mmol g-1 h-1 in flow cell, surpassing most reported carbon catalysts. Through selective chemical titration of C=O, C-OH, and COOH groups, we found that C=O species contributed to the most electrocatalytic activity and were the most active sites for 2 e- ORR, which were corroborated by theoretical calculations.

The production of functionalized anilines by chemoselective hydrogenation of nitroarenes occupies an important position in the chemical industries. Recently, cobalt and nitrogen codoped carbon (Co–...

Mesoporous carbon with high mesoporosity could overcome the diffusion limitations in the application fields requiring fast mass transportation. However, traditional templating approaches-derived carbons usually own low mesoporosity resulted from the microporosity dominated nanostructure. Herein, we developed a versatile method adopting self-made Fe(OH)3 as coordinative template to absorb phenols by coordination effect and in situ inducing the polymerization of phenol and formaldehyde to form phenolic resin at Fe(OH)3. Then, the generated H2O and the derived iron oxide from the template upon high temperature could serve as activation regents and mold constructing rich mesoporosity and graphitic structure. The derived products possess foam-like morphology, worm-like mesoporous structure, good graphitization degree, large surface area (1590 m2/g), large pore volume (2.86 cm3/g), uniform pore size distribution (~ 3.1 nm), ultrahigh mesoporosity (98.6%) and exhibit an excellent energy storage performance for aqueous supercapacitor including large energy density of 30.6 Wh/kg, superior capacitance retention of 76.8% and long cycling stability with near 100% capacitance retention after 10 000 cycles at large current density of 20 A/g. The superior capacitance retention for SC implies a wide application potentiality of the developed mesoporous carbon in other fields closely related to fast mass transfer such as catalysis, sorption and so on.

The efficient capture of radioiodine from the waste of nuclear industries is a growing priority for the safe development of nuclear energy. However, because the iodine adsorption rate of previously reported adsorbents is very slow, they are inadequate for use in an actual emergency such as radioiodine leakage in a nuclear accident. Herein, a nitrogen-rich covalent triazine–piperazine-based porous polymer (n-CTP) was successfully synthesized via a mild one-step solvothermal route. The large pore size and abundant N-heterocyclic groups (with a nitrogen content as high as 39.69%) of n-CTP are beneficial for the diffusion and adsorption of I2, and they have the ability to decrease the adsorption time. The ability of n-CTP to adsorb iodine vapor was examined, and the results show that n-CTP possesses a faster adsorption rate (1.58 g g−1 h−1) than most iodine-capturing covalent organic polymers (COPs), excellent iodine uptake capacity (4.19 g g−1), satisfactory selectivity, and can be reused for at least three cycles without a significant loss of iodine uptake. FT-IR and Raman analyses revealed that the mechanism of iodine capture is attributed to the charge transfer interactions between n-CTP and the guest iodine. In addition, n-CTP also exhibits high iodine capture capacity (2.88 g g−1) and fast adsorption rate in iodine solutions. Thus, n-CTP has the potential to be applied to the rapid removal and enrichment of radioiodine in spent fuel reprocessing and has the ability to prevent environmental contamination in the case of nuclear accidents.

Heteroatom-doping in metal-nitrogen-carbon single-atom catalysts (SACs) is considered a powerful strategy to promote the electrocatalytic CO

The Second Member of Kongdian Formation (Ek2) shale oil system is a set of thick organic-rich lacustrine shales with great shale oil resources potential. The shales are oil-prone with high organic ...

To realize the flow visualization of shock train structures by Schlieren measurements in a square-to-circular transition isolator, a high-precision conformal optical window was manufactured by fly-cutting technology. According to the light refraction principle, the window’s outer surface was iteratively optimized based on the super-elliptic curves of the internal flow channel. Through tolerance analysis and processing parameter optimization, the transmitted wavefront error (RMS value) of the finished window was 0.823 λ ( λ = 632.8 n m ). Based on a z -type Schlieren apparatus, the high-precision Schlieren measurements were conducted through the window and processed by an image filtering process method. The results promote high-precision Schlieren observation towards square-to-circular transition isolators.

Ruthenium (Ru)-based catalysts, with considerable performance and desirable cost, are becoming highly interesting candidates to replace platinum (Pt) in the alkaline hydrogen evolution reaction (HER). The hydrogen binding at Ru sites (Ru-H) is an important factor limiting the HER activity. Herein, density functional theory (DFT) simulations show that the essence of Ru-H binding energy is the strong interaction between the 4 d z 2 orbital of Ru and the 1s orbital of H. The charge transfer between Ru sites and substrates (Co and Ni) causes the appropriate downward shift of the 4 d z 2 -band center of Ru, which results in a Gibbs free energy of 0.022 eV for H* in the RuCo system, much lower than the 0.133 eV in the pure Ru system. This theoretical prediction has been experimentally confirmed using RuCo alloy-nanosheets (RuCo ANSs). They were prepared via a fast co-precipitation method followed with a mild electrochemical reduction. Structure characterizations reveal that the Ru atoms are embedded into the Co substrate as isolated active sites with a planar symmetric and Z-direction asymmetric coordination structure, obtaining an optimal 4 d z 2 modulated electronic structure. Hydrogen sensor and temperature program desorption (TPD) tests demonstrate the enhanced Ru-H interactions in RuCo ANSs compared to those in pure Ru nanoparticles. As a result, the RuCo ANSs reach an ultra-low overpotential of 10 mV at 10 mA cm-2 and a Tafel slope of 20.6 mV dec-1 in 1 M KOH, outperforming that of the commercial Pt/C. This holistic work provides a new insight to promote alkaline HER by optimizing the metal-H binding energy of active sites.

This paper proposes a method based on a single-probe scanning system for measuring the profile error of an artifact. Our system employs the movement accuracy of a single sensor to achieve a virtual multi-sensor configuration that can function like a traditional multi-sensor. This novel virtual multi-probe scanning system and its corresponding method have the following benefits: (a) A high-accuracy profile can be reconstructed free of the guidance error of the scanning stage. The reconstructed profile has a very high lateral resolution, depending on the lateral resolution (µm level) of the probe. (b) Sensor drift can be restrained using our method, based on the principle of differential reconstruction. The high steep profile can also be measured with a scanning system moving along the measuring direction, thus extending the measuring range. We developed the measurement system and tested the effects of noise, drift, and other factors on the reconstruction results. Finally, some optical surfaces were measured, and comparisons were made between the results obtained from our method and those of a Zygo interferometer. There was high agreement between the two methods, with a deviation of approximately 0.1 μm.

Atomically dispersed transition metal sites have been extensively studied for CO

Developing an efficient approach of transforming biomass waste to functional carbon-based electrode materials applied in supercapacitor offers an important and high value-added practical application due to the abundance and considerable low price of biomass wastes. Herein, a hierarchical carbon functionalized with electrochemical-active oxygen-containing groups was fabricated by microwave treatment from the biomass waste of camellia oleifera. The obtained mesoporous carbon (MAC) owns nanosheet morphology, rich mesoporosity, large surface area (1726 m2/g) and very high oxygenic functionalities (16.2 wt%) with pseudocapacitive activity. Prepared electrode of supercapacitor and tested in 2.0 M H2SO4, the MAC exhibits an obvious pseudocapacitive activity and achieved a superior supercapacitive performance to that of directly activated carbon (DAC-800) including high specific capacitance (367 F/g vs. 298 F/g) and better rate performance (66% vs. 44%). The symmetrical supercapacitor based on MAC shows a high capacity of 275 F/g, large energy density of 9.55 Wh/kg (at power density of 478 W/kg) and excellent cycling stability with 99% capacitance retention after 10000 continuous charge-discharge, endowing the obtained MAC a promising functional material for electrochemical energy storage.

An oxide catalyst plays an important role in environmental catalysis. Metal chlorides are widely used as precursors in the preparation of oxide catalysts. However, residual chlorine usually influen...