炼钢过程中环保型炉外精炼技术的应用与挑战

全球范围内对环境保护重视程度的显著提升,使得钢铁业需要重新审视其生产方式对环境造成的负担。行业转型的背景下,炉外精炼技术创新扮演了重要角色,此技术不仅显著提升钢粒品质,而且提高生产过程的效率,对于环境保护发挥了重要的作用。本研究针对当前环保议题下钢铁行业炉外精炼技术的具体应用与所面临的各种挑战进行了深入剖析,旨在为钢铁产业转型升级提供理论支持与实践指导。

Lotus root-like RuIr alloys with close-packed(0001)branches:Strain-driven performance for acidic water oxidation

Achieving composition tunability and structure editability of nanoalloys with high level strain may be an efficient strategy to remarkably boost catalytic performance toward oxygen evolution reaction(OER)in acidic water oxidation.Herein,lotus root-like RuIr alloys with native micro-strain were constructed by an epitaxial growth of Ru-richened hcp-(0001)branches on Ir-richened fcc-(111)seeds using a polyol thermal synthesis strategy.The resultant Ru_(60)Ir_(40) alloy shows an OER overpotential of 197 mV at 10 mA cm^(-2) and a Tafel slope of 46.59 mV dec^(-1),showing no obvious activity decay for 80 h continuous chronopotentiometry test in 0.5 M H_(2)SO_(4).The related characterizations including X-ray absorption fine structure(XAFS)spectroscopy and density functional theory(DFT)calculations show that that the remarkably improved activity of the lotus root-like alloy can be attributed to the(0001)facet-triggered strain,which can efficiently optimize the electronic band structure of the active metal and the weakening of the chemisorption of oxygen-containing substances to boost OER electrocatalysis.Therefore,this work provides a new strategy to designing a class of advanced electrocatalysts with high strain using diverse nanostructures as building materials for carbon-free clean energy conversion systems.

Pb induced dislocation defects of PtCo systems: Strain-triggered oxygen reduction reaction for PEMFC

Design and development of advanced electrocatalysts with high performance and low Pt consumption are crucial for reducing the kinetic energy barrier of the cathode oxygen reduction reaction(ORR)and improving the efficiency of proton exchange membrane fuel cells(PEMFC).In this study,we demonstrate a Pb-modulated PtCo system for efficient ORR,in which the inclusion of Pb in ternary alloys induces dislocation defects due to the significant difference in atomic radius.Dislocation-PtCoPb was confirmed to exhibit significantly higher ORR activity and stability in acidic ORR.In practical PEMFC applications,it outperforms the corresponding commercial Pt/C with a mass activity of 0.58 A·mgPt^(-1),making it a promising alternative to state-of-the-art Pt-based catalysts.The combination of experimental results and density functional theory(DFT)calculations offers valuable atomic-level insights into the dislocation structures.Pb with a larger atomic radius is located in the lattice stretching region below the dislocation slip plane,forming a structure similar to a Cottrell atmosphere,which reduces the dislocation energy and puts the system in a lower energy state.The Cottrell atmosphere pins the dislocation structure and stabilizes the ternary alloy.By adjusting the amount of added Pb,a moderate level of dislocation density induces a tuned strain effect,thereby enhancing the electrocatalytic mechanism by optimizing the electronic structure of the alloy surface and the adsorption and desorption of oxygen species.This work provides valuable insights into the design and development of lattice dislocation defect structures to trigger strain effects for improving ORR performance.

Small amount but big impact:Trace oxygen interstitially inserted PtCu alloys by microalloying for efficient oxygen reduction catalysis

The introduction of small size non-metal elements(e.g.,oxygen)into solid solution alloys may be a promising strategy for fabricating efficient Pt-based catalysts with high activity and stability toward oxygen reduction reaction(ORR).Herein,oxygen interstitially inserted PtCu(O-PtCu)alloys are firstly designed by an oxygen-microalloying strategy,through ultraviolet(UV)irradiation-assisted galvanic replacement in an aqueous solution containing H_(2)PtCl_(6) and Cu_(2)O nanowires as sacrificial templates.The obtained O-PtCu alloys feature a typical face-centered cubic(FCC)structure with majority Pt,Cu atoms as building bricks and trace interstitial oxygen(1.65 wt.%)existed in the octahedral sites surrounding Cu atoms,leading to a short-range disordered structure.The alloy reaches a recorded half-wave potential of 0.96 V(vs.reversible hydrogen electrode(RHE))and mass activity of 0.48 A·mgPt^(−1),much higher than those of commercial Pt/C.During the accelerated degradation test(ADT),the mass activity lost only 4.2%after 10k cycles,while the commercial Pt/C lost 66.7%under the same conditions.Compared with pure Pt and undoped PtCu alloy,the remarkably improved performance can be attributed to the lattice distortion and energy band reconstruction caused by the interstitial oxygen atoms in form of Cu–O bonds.Moreover,the stable Cu–O bonds delay the possible place exchange between surface Pt atoms and surface-adsorbed oxygen species,thereby hindering Pt dissolution,providing a new paradigm to address Pt degradation issue.Therefore,the introduction of interstitial oxygen into Pt-based alloys may be a facile and smart strategy for the development of advanced Pt-based alloys electrocatalysts.

Recent advances in crystalline carbon nitride for photocatalysis

Semiconductor photocatalytic technology has become one of the most important means to solve the current energy shortage and environmental pollution. Compared with the traditional photocatalysts, graphite carbon nitride has a wider range of light-harvesting and more stable physical and chemical properties. However, traditional thermally induced polymerization of nitrogen-containing precursors produces the melon-based carbon nitride solids with an amorphous or semi-crystalline structure, resulting in low conductivity and moderate photocatalytic activity. Recently, crystalline carbon nitride has attracted more and more attention in improving photocatalytic performance. Some significant progress regarding crystalline carbon nitride for the preparation of solar-fuel and environmental purification has also been made.This review describes the recent advances in the design and synthesis of crystalline carbon nitride photocatalysts. A brief description of the unique physical and chemical properties of crystalline carbon nitride was given. Later, the synthetic and modification strategies are being introduced. Then, the photocatalytic application of crystalline carbon nitride was discussed, mainly including photocatalytic H2 production,photocatalytic CO2 reduction, and photocatalytic degradation of pollutants. Finally, the challenges and future directions of crystalline carbon nitride photocatalysts are briefly introduced.