Silver Decoration Research Articles

A strategy to reutilize silver nanoparticles on silicon nanowires via photocathodic activation for enhanced and sustainable hydrogen evolution

The development of electrodes for hydrogen evolution via water splitting in a neutral electrolyte is highly desirable, especially considering that natural water resources such as seawater typically have a neutral pH. In this study, silicon nanowires (SiNWs) arrays with uniform silver (Ag) decoration are prepared as a cathode material, which exhibits excellent and stable electrochemical performance for neutral water electrolysis. Ag ions, utilized in the preparation of SiNWs through metal-assisted chemical etching technique, are retained and decorated within the SiNWs array without undergoing a dissolution process, referred to as Native SiNWs. Remained Ag+ ions on the SiNWs are activated photocathodically and reduced to Ag0, resulting in a significantly enhanced performance as an electrocatalyst for hydrogen evolution reaction (HER). Hence, this photocathodic activation of Native SiNWs (PCA-Native SiNWs) eliminates the need for additional cocatalyst deposition for HER, utilizing the Ag ions employed in the SiNWs preparation process. This enhancement in HER activity is exclusively observed by photocathodic activation, not by cathodic activation without light irradiation, indicating the crucial role of photoelectrons in SiNWs under light irradiation for the activation. Additionally, the nanowire structure serves as an ideal platform for Ag nanoparticles, providing sufficient surface area, resulting in excellent dispersion and an increased number of active sites. Furthermore, PCA-Native SiNWs demonstrates outstanding electrochemical stability for over 60 h, with no significant reduction in current density or structural degradation in a neutral electrolyte. Several characterizations and electrochemical analyses have been conducted to elucidate the in-situ decoration of Ag nanoparticles on SiNWs and investigate the surface chemistry for the activation mechanism. This work introduces a new perspective on using Ag-decorated SiNWs directly as an electrocatalyst for effective hydrogen evolution in a neutral media.

Silver Decoration of Vertically Aligned MoS2-MoOx Nanosheets: A Comprehensive XPS Investigation.

This study investigates the simultaneous decoration of vertically aligned molybdenum disulfide nanostructure (VA-MoS2) with Ag nanoparticles (NPs) and nitrogen functionalization. Nitrogen functionalization was achieved through physical vapor deposition (PVD) DC-magnetron sputtering using nitrogen as a reactive gas, aiming to induce p-type behavior in MoS2. The utilization of reactive sputtering resulted in the growth of three-dimensional silver structures on the surface of MoS2, promoting the formation of silver nanoparticles. A comprehensive characterization was conducted to assess surface modifications and analyze chemical and structural changes. X-ray photoelectron spectroscopy (XPS) showed the presence of silver on the MoS2 surface. Scanning electron microscopy (SEM) confirmed successful decoration with silver nanoparticles, showing that deposition time affects the size and distribution of the silver on the MoS2 surface.

Silver nanoparticle−decorated MnO2 for promoted Mn4+/Mn2+ redox reaction in aqueous Zn−MnO2 batteries

Rechargeable aqueous Zn−MnO2 batteries have garnered increasing attention recently due to intrinsic safety, high theoretical capacity, appealing output voltage, and low material cost. However, challenges still exist in exploring for high−performance manganese oxides capable of delivering comparable capacity to the Zn anode. Herein, a composite material made of layered MnO2 decorated with Ag nanoparticles (Ag NPs) can be prepared by a one−step hydrothermal reaction. The silver decoration strategy can provide facile electron transport of the composite cathode and induce structural vacancies via forming Ag−O−Mn bond. These features enable the AgMO cathode to exhibit smaller charge−transfer resistance (23.0 vs 41.3 Ω) and accelerated ion transport kinetics (1.25×10−10 vs 3.90×10−11 cm2 s−1). More importantly, the presence of Ag NPs is found to promote the reaction kinetics of Mn4+/Mn2+ redox. By taking these advantages, the AgMO sample exhibits a higher attainable capacity of 333 mAh g–1 at 0.3 A g–1 compared with the Ag−free counterpart (MO, 268 mAh g–1). Moreover, AgMO demonstrates better rate performance with the discharge capacity of 109 mAh g–1 at 8 A g–1 (90 mAh g–1 for MO), and a specific capacity of 93 mAh g–1 can still be achieved for AgMO after 2000 cycles at 4 A g–1 (55 mAh g–1 for MO). This work presents a holistic approach to enhance the energy storage capability of MnO2 cathode in rechargeable aqueous Zn−ion batteries.

Hydrogen Diffusion and Trapping Behaviour in DP Steels: An Electrochemical Hydrogen Permeation Study

Advanced high-strength steels (AHSSs) are widely used in the automotive industry as they possess high strength-to-weight ratio. This allows designing light vehicles with better passenger safety, lower fuel consumption, and CO2emissions. Dual-phase (DP) steels are very attractive among the AHSSs because of their optimal combination of high tensile strength (up to 1.2 GPa), high ductility (10 % or more), and good formability due to their two-phase microstructure (ferrite and martensite). However, the use of DP steel is associated with an increased risk of mechanical degradation in the presence of hydrogen environment, i.e., hydrogen embrittlement (HE). The HE susceptibility of DP steel is mainly determined by hydrogen entry, diffusion, and trapping events in the microstructure (i.e., hydrogen interaction with metal). There are various methods to study the above mechanism in metals like hydrogen charging-tensile test, thermal desorption spectroscopy, silver decoration, scanning kelvin probe microscopy, electrochemical hydrogen permeation, etc. Among these, electrochemical hydrogen permeation using Devanathan - Stachurski (DS) cell is a simple and most widely used technique.In this work, electrochemical hydrogen permeation was used to understand the role of microstructural features on hydrogen diffusion and trapping behaviour in DP-980 steel. It was identified that the phase fraction and its morphological features influence the hydrogen diffusion behaviour. The challenges in layout, design and integration of conventional DS cell into a tensometer and the effect of pre-strain (ex-situ) and tensile stress (in-situ) loading on hydrogen diffusion and trapping in DP-980 will be discussed. The applied elastic stress (i.e., 50 % of YS) during the permeation test resulted in a slight increase in Dapp from 5.4 ± 0.1 × 10- 7 to 5.9 ± 0.69×10-7 cm2s-1 and a slight reduction in NT from 1.08 ± 0.01 × 1021 to 1.0 ± 0.13× 1021 sites cm-3 compared to the no-stress condition. At 110 % of YS, the highest value of iss is 169 ±10.6 (µAcm-2) and a significant increase in the value of Capp to 3.6 ± 0.3 × 10-4 (molHcm-3 ), whereas no significant change in values of Dapp and NT were observed at 110 % YS compared to no stress and 50 % of YS. This could be due to the elastic deformation of martensite at 110 % of YS. The lattice expansion of martensite under elastic tensile stress can accommodate more interstitial hydrogen, thereby higher steady-state permeation current is observed. At 125 % of YS, the value of Dapp (2.86×10-7 cm2s-1) is approximately 50 % less compared to the value observed for the un-stressed specimen (5.4 ± 0.1×10-7 cm2s- 1). The value of NT (2.11×1021 cm-3) is approximately two times higher than that of the value (1.08×1021 cm-3 ). Plastic deformation of both ferrite and martensite results in increased dislocation density (hydrogen trap sites) at 125 % of YS. The sample failed during the hydrogen permeation test and when it is subjected to 125 % YS. It exhibited distinct fractographic features along the thickness of the sample. Quasi-cleavage and intergranular cracks were observed near the cathodic surface. Whereas, dimples and microvoids which are complete ductile features, were observed near the anodic surface. At 125 % of YS a significant decrease in the value of DL 0.6×10-6 cm2s-1 was observed. Whereas the value of NTrev increased to 4.0 ± 0.2×1019 cm-3 from 3.0 ± 0.15×1019 cm-3.An attempt was made to study the hydrogen transport behaviour at the local spot by appropriate modification of conventional DS cell. The fabrication challenges and the potential application of such an instrument will be elucidated.

Oxygen vacancy-engineered BiOCl nanoflake with silver decoration for enhanced photocatalytic CO2 reduction at solid-gas interface

Photocatalytic conversion of CO2 into valuable chemicals is an attractive way to mitigate the greenhouse effect. However, the poor mass transfer of CO2 in a liquid-phase reaction limits its conversion rate and carbon product selectivity. Here, we developed a gas-phase photocatalytic CO2 reduction by Ag/BiOCl-oxygen vacancy nanoflakes (Ag/BiOCl-OV NFs) where the catalytic reaction occurs at the solid–gas interface between Ag/BiOCl-OV and CO2/vapor reactants. Such a solid–gas system allows rapid adsorption/desorption of CO2 on the surface of photocatalysts, enhanced light absorption and electron-hole separation, resulting in promoted photocatalytic reaction rate and CO selectivity compared to the solid–liquid systems. By supporting Ag/BiOCl-OV NFs on a photothermal substrate that has broadband light absorption to perform local heating for in-situ photothermal enhanced photocatalytic reaction. The synergistic effect of Ag nanoparticles, OVs and photothermal, the highly-selective CO product shows an evolution rate of 76 μmol g-1h−1, 17.6 times higher than that of pure BiOCl NFs.

Silver decoration of Cr2O3 nanoparticles: Facile preparation of Cr2O3 nanoparticles and Ag–Cr2O3 nanocomposites and characterization of their antibacterial activity and ability to photocatalytically degrade organic wastes under visible light

An eco-friendly, single-step process was adopted for the preparation of Cr2O3 nanoparticles (CR-NPs), and different concentrations of Ag were doped into the CR-NPs through liquid impregnation to synthesize a series of Ag-CRNPs composites. In order to prevent agglomeration, chemical transformation, and weak adhesion of Ag to CR-NPs, a mechanical process of circular-motion grinding and high-temperature treatment in a sealed condition were used. Well-defined heterojunctions were successfully formed between Ag and CR-NPs. In comparison to the CR-NPs, the Ag-doped CR-NP composites exhibited excellent performance in photocatalytic and antibacterial applications. Under visible light (VL), the best-performing composite (2 %-Ag decorated CR-NPs) showed 96 %, 79 %, and 57 % decomposition of methylene blue, Congo red, and tetracycline, respectively, in 100 min, which was attributed to a synergetic effect in the composites. The rate constant of the photocatalytic reaction is 14 times higher than that of the reaction without a photocatalyst. The enhanced efficiency was attributed to a reduced bandgap, prolonged retention of photogenerated electron–hole pairs, an increased amount of active spots, and increased absorption of VL. Similarly, the best-performing composite exhibited excellent antibacterial activity against Escherichia coli and Staphylococcus aureus with zones of inhibition of 15.4 and 15.1 mm, respectively. The 2 %-Ag decorated CR-NPs were the most efficient and exhibited robust recyclability until the fifth cycle (≥90 %). The photocatalytic activity was primarily driven by reactive oxygen species, holes and hydroxyl radicals.

Boosting Copper Biocidal Activity by Silver Decoration and Few-Layer Graphene in Coatings on Textile Fibers.

The outbreak of the Coronavirus disease 2019 (COVID-19) pandemic has highlighted the importance of developing antiviral surface coatings that are capable of repelling pathogens and neutralizing them through self-sanitizing properties. In this study, a novel coating design based on few-layer graphene (FLG) is proposed and silver-decorated micro copper flakes (CuMF) that exhibit both antibacterial and antiviral properties. The role of sacrificial anode surfaces and intrinsic graphene defects in enhancing the release of metal ions from CuMF embedded in water-based binders is investigated. In silico analysis is conducted to better understand the molecular interactions of pathogen-repelling species with bacterial or bacteriophage proteins. The results show that the optimal amount of CuMF/FLG in the coating leads to a significant reduction in bacterial growth, with reductions of 3.17 and 9.81 log for Staphylococcus aureus and Escherichia coli, respectively. The same coating also showed high antiviral efficacy, reducing bacteriophage phi6 by 5.53 log. The antiviral efficiency of the coating is find to be doubled compared to either micro copper flakes or few-layer graphene alone. This novel coating design is versatile and can be applied to various substrates, such as personal protective clothing and face masks, to provide biocidal activity against both bacterial and viral pathogens.

Scientific Research on a Gold- and Silver-Inlaid Bronze Zun from the Han Dynasty

The bronze Zun was one of the more prevalent high-class wine containers of the Han dynasty, representing the highest level of decoration in bronze at the time. However, little has been reported about its technical characteristics and scientific value. In this paper, the samples were selected for analysis based on scientific analysis, following the principle of “minimal intervention”, and a bronze Zun from the Han dynasty in the Gansu Provincial Museum collection was studied using ultra-deep field microscopy, X-ray flaw detection, X-ray fluorescence spectrometry (XRF), scanning electron microscopy (SEM), and energy spectrometry (EDS). The results show that the gold and silver decoration on the bronze is inlaid rather than gilt. Secondly, the body and lid of the vessel are molded in one shot, with the bird-head-shaped and animal-foot-shaped components cast separately and then attached to the lid and body. Thirdly, the corrosion of the bronze Zun is characterized by the copper matrix being corroded first and most severely, followed by the silver and, finally, the gold. The high purity of the gold wire embedded in this bronze Zun, the fine width of gold wire (154–190 μm), and the magnificent decoration show the excellent processing technology level of the precious metal and the high aesthetic level of ancient man during the Han dynasty. The results of the analysis of this bronze Zun can provide an essential reference for research on bronze vessels of the same type, the techniques of gold and silver misalignment, and the development of the history of bronze manufacture and technology during the Han dynasty.

Effect of inclusions on the hydrogen embrittlement of martensitic medium-Mn steel

In this study, we investigated the hydrogen embrittlement (HE) of martensitic medium-Mn steels with varying levels of S and Ti contents using thermal desorption analysis, silver decoration, slow strain rate tensile testing, and fractography. The S or S–Ti added specimens demonstrated higher HE resistance compared to the S-free specimens. This is because the S or S–Ti added specimens had a large volume fraction of fine MnS or Ti(C,N)–MnS complex inclusions with a size less than ∼1 μm, which provide strong irreversible H trap sites. However, coarse elongated inclusions were found to be detrimental to HE resistance. Therefore, we concluded that to improve the HE resistance of martensitic medium-Mn steel, it is important to distribute a large volume fraction of fine MnS or Ti(C,N)–MnS complex inclusions without coarse elongated ones.

Apex-Confined Plasmonic Tip for High Resolution Tip-Enhanced Raman Spectroscopic Imaging of Carbon Nanotubes.

This paper reports a handy technical scheme to decorate atomic force microscopy (AFM) tips toward tip-enhanced Raman spectroscopy (TERS) applications. The major attraction of these homemade tips lies in that silver decoration can be confined at the apex of commercial tips by the means of an AFM-controlled electrochemical reaction. The reduction of Ag+ occurs in a highly sealed environment to secure the metal coating efficiency. Key factors include silver nitrate solution to provide Ag+, ambient relative humidity and temperature in a humidity cell, electric potential bias, and tip-surface distance. Subsequently, these silver-coated tips are evaluated for TERS measurement of carbon nanotubes (CNTs) so that both morphological and chemical characteristics of CNTs are concurrently obtained. The Raman spectra reveal that our plasmonic tip competently possesses an ∼30-fold local field signal increase and the corresponding TERS image laterally resolves at the single-pixel level.

Spectroscopic and mass spectrometry-based in-situ investigation of a 17th-century handwritten academic diploma on illuminated parchment

In 2008, more than 300 ancient scrolls, some of which were preciously illuminated, were recovered in Chicago (USA) after being stolen and illegally exported. These scrolls consisted of private and public documents, including papal and royal, dating from the 14th to the 19th century. The scrolls were returned to Italy and 42 of them, known as the Chicago Parchments, are now preserved at the State Archives of Bari (Italy). An illuminated academic diploma from the 17th century, known as doctoratus privilegium, was among them, and it was of particular interest to restorers and conservation scientists. To identify the pigments, painting binders, and animal skin origin of the parchment, non-invasive analyses were carried out on several points using portable X-ray fluorescence (XRF), µRaman, and fibre optic reflectance spectroscopy (FORS). Gold and silver decorations were confirmed by XRF, highlighting the significance of the document. A quasi-non-invasive sampling approach was used to analyze the painting binders by applying a trypsin-chymotrypsin enriched hydrogel for in situ digestion of the proteinaceous material. The extracted binders were successfully identified as bovine and rabbit glues by both matrix-assisted laser desorption/ionization with time-of-flight mass spectrometry (MALDI-ToF-MS) and reversed-phase liquid chromatography with electrospray ionization tandem mass spectrometry (RPLC-ESI-MS/MS). By using bottom-up proteomics, the sheep skin origin of thin parchment samples was established from very small fragments that were digested in solution with trypsin.

A Study of Silver Decoration on Carbon Nanotubes via Ultrasonic Chemical Synthesis and Their Reinforced Copper Matrix Composites.

The homogeneous distribution of carbon nanotubes (CNTs) in the Cu matrix and good interfacial bonding are the key factors to obtain excellent properties of carbon nanotube-reinforced Cu-based composites (CNT/Cu). In this work, silver-modified carbon nanotubes (Ag-CNTs) were prepared by a simple, efficient and reducer-free method (ultrasonic chemical synthesis), and Ag-CNTs-reinforced copper matrix composites (Ag-CNTs/Cu) were fabricated by powder metallurgy. The dispersion and interfacial bonding of CNTs were effectively improved by Ag modification. Compared to CNTs/Cu counterparts, the properties of Ag-CNTs/Cu samples were significantly improved, with the electrical conductivity of 94.9% IACS (International Annealed Copper Standard), thermal conductivity of 416 W/m·k and tensile strength (315 MPa). The strengthening mechanisms are also discussed.

The Microstructure Characteristics Evolution of Bulk High-Purity Silver for High Relief Application

Silver products with high relief have become popular in the silver decoration industry. However, it is difficult to obtain these products through conventional processing at ambient temperature. The aim of this work is to solve this problem by increasing the deformation temperature. Detailed studies were conducted on the evolution of microstructure characteristics in bulk high-purity silver by electron backscatter diffraction (EBSD) to achieve high-relief applications at elevated temperatures. The high temperature sample is mainly composed of recrystallized and substructured grains, exhibiting a more stable state than the ambient temperature sample. More than 70% annealing twins are observed in the hot-working sample. They are characterized by the amount of Σ3n-type triple grain boundary junctions within large grain clusters formed by multiple twinning. These particular boundaries improve the intergranular corrosion resistance and degradation, which is significantly essential for high-purity silver jewelry exposed to sweat and air. The closed multi-coining processes at different temperatures were conducted subsequently. The performance of workpieces demonstrates that increasing the deformation temperature is a viable alternative for producing durable high-relief silver products.

Effect of Microstructure on Strain Aging and Hydrogen Embrittlement Behavior of Bake Hardening Steels

The strain aging and hydrogen embrittlement behavior of two bake hardening (BH) steels with different microstructures were investigated in this study. The single-phase BH steel was composed of fully ferrite, while the dual-phase BH steel consisted of ferrite and 3 % martensite. The BH index and aging index (AI) of the two BH steels were measured to compare the effect of microstructure on strain aging behavior. As a small amount of martensite is present in the dual-phase BH steel, the BH index value of the dual-phase BH steel was higher than that of single-phase BH steel, and the AI showed a relatively low value. After the BH steels were pre-strained up to 20% and electrochemically pre-charged with hydrogen, on the other hand, a slow strain rate test (SSRT) was carried out to examine the effect of pre-strain on hydrogen embrittlement behavior. The silver decoration technique and thermal desorption analysis (TDA) were performed to understand the hydrogen embrittlement mechanism from the standpoint of hydrogen trapping. Regardless of pre-strain the dual-phase BH steel had lower hydrogen embrittlement resistance than the single-phase BH steel because martensite formed in the dual-phase BH steel acts as a reversible hydrogen trap site. The hydrogen embrittlement resistance of the two BH steels decreased with increasing amount of pre-strain which increases dislocation density. Based on these results, it can be said that the introduction of martensite and dislocation in BH steels have a negative impact on hydrogen embrittlement resistance.

Silver/carbon co-decorated hollow TiO2 catalyst drives the efficient photocatalytic degradation/catalytic hydrogenation of 4-nitrophenol

The excellent photocatalytic degradation/catalytic reduction of phenolic pollutants still is a challenge. Here, we report a new silver/carbon co-decorated hollow TiO2 photocatalyst (Ag/C-TiO2) by depositing Ag NPs on the surface of carbon decorated hollow TiO2 sphere. This preparation process mainly involves in the synthesis of CPS@TiO2 template, the immobilization of silver ions, the preparation of carbon co-decorated hollow TiO2, and the formation of Ag/C-TiO2 photocatalyst. The as-synthesized Ag/C-TiO2 photocatalyst exhibits a complete removal (100%) of phenolic pollutants (phenol or 4-nitrophenol) under simulated sunlight due to the synergistic effect of silver decoration and carbon species. Notably, corresponding 4-aminophenol is achieved almost quantitatively towards the hydrogenation of 4-nitrophenol. Especially, the Ag/C-TiO2 photocatalyst exhibits a good stability and recyclability towards the photocatalytic degradation/reduction of 4-NP. Therefore, this work presents a rational design concept of highly efficient photocatalysts for environmental remediation.

Archaeological site Doljani – Dubine, municipality of Čapljina in Bosnia and Herzegovina. A contribution to the research of the lower course of the river Neretva

Archaeological site Doljani – Dubine, municipality of Čapljina in Bosnia and Herzegovina. A contribution to the research of the lower course of the river Neretva

Female Jewelry of the Mongolian People in the Collection of the V. A. Obruchev Kyakhta Local Museum

This article examines the Mongolian female jewelry collection of the Kyakhta Local Museum amounting to almost a hundred and fifty items. The collection started with expeditions of the Russian Geographical Society in the early twentieth century and continued throughout the Soviet period when it was significantly enlarged with items from various regions of Buryatia. According to the museum’s documents, and most of the items are still unidentified, the collection consists of scattered items or their individual elements which need proper research and technical expertise. During their examination of the said items, the authors solve several problems, i.e. they analyse and describe the art piece, the semantics of the ornamentation, identify the scrambled elements and pieces of jewelry used in the traditional costume of the Buryat regions. The authors use the iconographic, iconological, and comparative methods. The full set of female jewelry for the Mongolian people adorns the head, the neck, the chest, the shoulders, the waist and both arms. The article only focuses on headpieces and items worn hanging from the temples all the way down to the chest. It includes the description of silver decorations used for the top of male and female hats, and techniques for their differentiation. The study attempts to attribute the jewelry to define its affiliation with a specific Buryat ethnic group, as different areas of Buryatia and Mongolia have their own variations and artistic identities expressed in the traditional costume of their tribes and families. The article describes three items of Mongolian female jewelry. The authors aim to continue the research by focusing on each group of female jewelry attire with reference to comparable material from different museums.

Micro-axial cracking in unnotched, cold-drawn pearlitic steel wire: Mechanism and beneficial effect on the resistance to hydrogen embrittlement

Effects of cold drawing ratio (CDR) on the microstructure, tensile properties, H absorption and hydrogen embrittlement (HE) of pearlitic steel wire were investigated by means of thermal desorption analysis, slow strain rate tensile testing, fractography and silver decoration. The ultimate tensile strength (UTS) and diffusible H content of unnotched tensile specimens were raised with increasing CDR due to the reduction of interlamellar spacing and the increase in dislocation density. Nevertheless, the resistance to HE was improved as the CDR became above 30% due to micro-axial cracking. Elongations of H-uncharged and charged specimens decreased until the CDR of 30%, and then were maintained despite of a continuous rise of UTS with increasing CDR further. This is because micro-axial cracking occurred in the specimens with CDRs above 30% so that tensile fracture was retarded. As the CDR was over ∼30%, a fracture mode changed from brittle fracture featured by tearing topography surface and cleavage to ductile-like fracture characterized by many dimples and micro-axial cracks. Micro-axial cracking occurred as follows: Some micro-cracks preexisted inside well-aligned pearlite colonies of specimens with CDRs above 30%. While an unnotched, H-uncharged specimen was strained, micro-cracks additionally formed to be coalesced. The merged cracks traversed the pearlite colonies to be propagated into neighboring misaligned colonies and grew along the direction of cold drawing and tensile deformation, resulting in micro-axial cracking. In H-charged specimens, H atoms near micro-cracks clustered into micro-cracks so that micro-axial cracking was accelerated and the regions near micro-cracks underwent ductile fracture, leaving many dimples.

Pre-straining alters hydrogen-assisted cracking site and local hydrogen diffusivity in a nitrogen-doped duplex steel

The pre-deformation effects of hydrogen embrittlement on nitrogen-doped duplex stainless steel were investigated using tensile testing. Hydrogen pre-charging and pre-straining were adopted, which increased the yield strength, but decreased the ductility. Silver decoration revealed that diffusible hydrogen was preferentially located in the ferrite or grain boundaries of the undeformed steel, whereas the 22% pre-strained steel had diffusible hydrogen in austenite. When deformed, the preferential plastic deformation path of the steel was in the ferrite; hence, the apparent diffusivity in ferrite decreased, while the austenite had a relatively high apparent hydrogen flux. Pre-straining suppressed macroscopic hydrogen diffusion and local diffusion in ferrite and austenite by increasing the dislocation density. The degree of the suppression of the local diffusion was more significant in ferrite than austenite. The changes in dislocation and hydrogen behaviors associated with pre-straining altered the cracking sites in the austenite and ferrite, and decreased hydrogen embrittlement susceptibility.

Highly dispersive trace silver decorated Cu/Cu2O composites boosting electrochemical CO2 reduction to ethanol

Selective CO2 electroreduction to C2+ products, especially ethanol, is regarded as a potential technology for CO2 utilization but is still a formidable challenge. Herein, we report the highly dispersive trace Ag decorated copper/copper oxide composite (Cu/Cu2O-Ag-x) for efficient electrochemical CO2 reduction to C2+ products, mainly containing ethylene and ethanol. Physical measurements confirm that the Ag decoration is an effective strategy to tune the surface electronic structure but without changing the valence and morphology of Cu. The performance evaluation of electrochemical CO2 reduction in a flow cell demonstrates that the activity and selectivity for ethanol production on Cu/Cu2O can be promoted by the trace Ag modification. The best catalyst, Cu/Cu2O with merely 0.6 at.% silver decoration, exhibits a significant enhancement in C2+ selectivity (60.9 %) as compared to the Ag-free Cu/Cu2O catalyst (50.4 %). Originated from the formed Cu-Ag sites and thus enhanced affinity with oxygen-adsorbed intermediates on Cu/Cu2O-Ag-x catalysts, the ethanol formation is favored with a greatly improved Faradaic efficiency (19.2 %) as well as partial current density (305 mA cm−2), which are superior to those of Ag-free counterpart (9.1 %, 105 mA cm−2). Moreover, the products selectivity remains stable even electrolysis at 900 mA cm−2 over 8 h, demonstrating the preeminent electrocatalytic stability.