Microstructural Heterogeneity and Property Variations in Cast and Vacuum Hot-Pressed CoCrPtB Alloy.

Limited research has been undertaken regarding the homogeneity of CoCrPtB alloy billets. A CoCrPtB alloy was processed through casting and vacuum hot pressing. This investigation delved into the interconnection between the secondary dendrite arm spacing (SDAS) in the as-hot-pressed samples and their corresponding attributes, specifically Vickers hardness and magnetic properties. Systematic sampling was conducted on the cross-sectional layer and longitudinal surface. Upon examination of the cross-sectional layer proximate to the uppermost region of the hot casting, a discernible parabolic trend was observed for the SDAS that exhibited a gradual increment from the peripheral regions toward the central area along the width. Simultaneously, the fraction of the dendrite phase displayed a consistent linear decline, attaining its peak value at the central portion of the billet. Conversely, on the longitudinal surface, SDAS and the fraction of the dendrite phase remained fairly uniform within the same column sampling regions. However, a notable divergence was identified in the central section, characterized by an augmented SDAS and diminished dendrite phase content. This inherent microstructural inhomogeneity within the CoCrPtB alloy engendered discernible disparities in material properties.

NAD(P)H-Inspired CO2 Reduction Based on Organohydrides.

The conversion of CO2 into value-added chemicals and fuels using stable, cost-effective, and eco-friendly metal-free catalysts is a promising technology to mitigate the global environmental crisis. In the Calvin cycle of natural photosynthesis, CO2 reduction (CO2R) is achieved using the cofactor NADPH as the reducing agent through 2e-/1H+ or H- transfer. Consequently, inspired by NAD(P)H, a series of organohydrides with adjustable reducibility show remarkable potential for efficient metal-free CO2R. In this review, we first summarize the photosensitizers for NAD(P)H regeneration and list the representative photoenzyme CO2R system. Then, we introduce the NAD(P)H-inspired organohydrides and their applications in redox reactions. Furthermore, we discuss recent progress and breakthroughs by utilizing organohydrides as metal-free CO2R catalysts. Moreover, we delve into the reaction mechanisms and applications of these organohydrides, shedding light on their potential as sustainable alternatives to metal-based CO2R catalysts. Finally, we offer insights into the prospects and potential directions for advancing this intriguing avenue of organohydride-based catalysts for CO2R.

Coupling capillary electrophoresis with mass spectrometry for the analysis of oxidized phospholipids in human high-density lipoproteins.

The oxidized 1-palmitoyl-2-arachidonoyl-sn-glycero-3-phosphocholine (ox-PAPC) products in human high-density lipoproteins (HDLs) were investigated by low-flow capillary electrophoresis-mass spectrometry (low-flow CE-MS). To accelerate the optimization, native PAPC (n-PAPC) standard was first analyzed by a commercial CE instrument with a photodiode array detector. The optimal separation buffer contained 60% (v/v) acetonitrile, 40% (v/v) methanol, 20 mM ammonium acetate, 0.5% (v/v) formic acid, and 0.1% (v/v) water. The selected separation voltage and capillary temperature were 20 kV and 23°C. The optimal CE separation buffer was then used for the low-flow CE-MS analysis. The selected MS conditions contained heated capillary temperature (250°C), capillary voltage (10 V), and injection time (1 s). No sheath gas was used for MS. The linear range for n-PAPC was 2.5-100.0 µg/mL. The coefficient of determination (R2 ) was 0.9918. The concentration limit of detection was 1.52 µg/mL, and the concentration limit of quantitation was 4.60 µg/mL. The optimal low-flow CE-MS method showed good repeatability and sensitivity. The ox-PAPC products in human HDLs were determined based on the in vitro ox-PAPC products of n-PAPC standard. Twenty-one ox-PAPC products have been analyzed in human HDLs. Uremic patients showed significantly higher levels of 15 ox-PAPC products than healthy subjects.

Facile Construction of CuFe-Based Metal Phosphides for Synergistic NOx - Reduction to NH3 and Zn-Nitrite Batteries in Electrochemical Cell.

The electrocatalytic nitrite/nitrate reduction reaction (eNO2 RR/eNO3 RR) offer a promising route for green ammonia production. The development of low cost, highly selective and long-lasting electrocatalysts for eNO2 RR/eNO3 RR is challenging. Herein, a method is presented for constructing Cu3 P-Fe2 P heterostructures on iron foam (CuFe-P/IF) that facilitates the effective conversion of NO2 - and NO3 - to NH3 . At -0.1 and -0.2 V versus RHE (reversible hydrogen electrode), CuFe-P/IF achieves a Faradaic efficiency (FE) for NH3 production of 98.36% for eNO2 RR and 72% for eNO3 RR, while also demonstrating considerable stability across numerous cycles. The superior performance of CuFe-P/IF catalyst is due tothe rich Cu3 P-Fe2 P heterstuctures. Density functional theory calculations have shed light on the distinct roles that Cu3 P and Fe2 P play at different stages of the eNO2 RR/eNO3 RR processes. Fe2 P is notably active in the early stages, engaging in the capture of NO2 - /NO3 - , O─H formation, and N─OH scission. Conversely, Cu3 P becomes more dominant in the subsequent steps, which involve the formation of N─H bonds, elimination of OH* species, and desorption of the final products. Finally, a primary Zn-NO2 - battery is assembled using CuFe-P/IF as the cathode catalyst, which exhibits a power density of 4.34 mW cm-2 and an impressive NH3 FE of 96.59%.

Hot-Pressing Deformation Yields Fine-Grained, Highly Dense and (002) Textured Ru Targets.

Ruthenium (Ru) is a refractory metal that has applications in the semiconductor industry as a sputtering target material. However, conventional powder metallurgy methods cannot produce dense and fine-grained Ru targets with preferred orientation. Here, we present a novel method of hot-pressing deformation to fabricate Ru targets with high relative density (98.8%), small grain size (~4.4 µm) and strong (002) texture. We demonstrate that applying pressures of 30-40 MPa at 1400 °C transforms cylindrical Ru samples into disk-shaped targets with nearly full densification in the central region. We also show that the hardness and the (002)/(101) peak intensity ratio of the targets increase with the pressure, indicating enhanced mechanical and crystallographic properties. Our study reveals the mechanisms of densification and texture formation of Ru targets by hot-pressing deformation.

Hot Deformation Behavior and Processing Maps of Pure Copper during Isothermal Compression.

In this study, pure copper's hot deformation behavior was studied through isothermal compression tests at deformation temperatures of 350~750 °C with strain rates of 0.01~5 s-1 on a Gleeble-3500 isothermal simulator. Metallographic observation and microhardness measurement were carried out of the hot compressed specimens. By analyzing the true stress-strain curves of pure copper under various deformation conditions during the hot deformation process, the constitutive equation was established based on the strain-compensated Arrhenius model. On the basis of the dynamic material model proposed by Prasad, the hot-processing maps were acquired under different strains. Meanwhile, the effect of deformation temperature and strain rate on the microstructure characteristics was studied by observing the hot-compressed microstructure. The results demonstrate that the flow stress of pure copper has positive strain rate sensitivity and negative temperature correlation. The average hardness value of pure copper has no obvious change trend with the strain rate. The flow stress can be predicted with excellent accuracy via the Arrhenius model based on strain compensation. The suitable deforming process parameters for pure copper were determined to be at a deformation temperature range of 700~750 °C and strain rate range of 0.1~1 s-1.

Determination of oxidized 1-palmitoyl-2-arachidonoyl-sn-glycero-3-phosphocholine products in human very low-density lipoproteins by nonaqueous low-flow capillary electrophoresis-mass spectrometry.

A simple and fast low-flow capillary electrophoresis-mass spectrometry (low-flow CE-MS) method has been developed to analyze oxidized 1-palmitoyl-2-arachidonoyl-sn-glycero-3-phosphocholine (ox-PAPC) products in human very low-density lipoproteins (VLDLs). Native PAPC standard was analyzed to optimize the low-flow CE-MS method. The optimal CE conditions included separation buffer (60% (v/v) acetonitrile, 40% (v/v) methanol, 0.1% (v/v) water, 0.5% (v/v) formic acid, 20 mM ammonium acetate), sheath liquid (60% (v/v) acetonitrile, 40% (v/v) methanol, 0.1% (v/v) water, 20 mM ammonium acetate), separation voltage (20 kV), separation capillary internal diameter (i.d.) (75 µm), separation capillary temperature (23˚C) and sample injection time (6 s). The selected MS conditions included heated capillary temperature (250°C), capillary voltage (10 V), and injection time (1 s). Sheath gas was not used in this study. The total ion chromatograms (TICs), extracted ion chromatograms (EICs) and MS spectra of native PAPC standard and its in vitro oxidation products showed good repeatability and sensitivity. To determine the ox-PAPC products in human VLDLs, the EICs and MS spectra of VLDLs were compared with the in vitro oxidation products of native PAPC standard. For native PAPC standard, the measured linear range was 2.5 - 100.0 µg/mL, and the coefficients of determination (R2) was 0.9994. The concentration limit of detection (LOD) was 0.44 µg/mL, and the concentration limit of quantitation (LOQ) was 1.34 µg/mL. A total of 21 ox-PAPC products were analyzed for the VLDLs of healthy and uremic subjects. The levels of 7 short-chain and 5 long-chain ox-PAPC products on uremic VLDLs were significantly higher than healthy VLDLs. This simple low-flow CE-MS method might be a good alternative for LC-MS for the analysis of ox-PAPC products. Furthermore, it might also help scientists to expedite the search for uremic biomarkers.

Electrochemical ammonia synthesis from nitrite assisted by in situ generated hydrogen atoms on a nickel phosphide catalyst.

Investigating green and effective means for ammonia synthesis is an important but challenging task. Electrochemical ammonia synthesis (EAS) from an indirect route (N2 → NOx → NH3) provides a feasible alternative strategy. The key step in this route is the reduction of NOx to NH3 instead of N2, which requires the investigation of efficient catalysts with high selectivity of NH3. Herein, we initially demonstrate a highly efficient electrochemical reduction of NO2- to NH3 with nickel phosphide (Ni2P) as the catalyst. The system exhibits low onset potential (0.2 V vs. RHE) and high faradaic efficiency (>90%) for EAS. Experimental results and theoretical calculations reveal that the in situ generated hydrogen atoms on the surface of Ni2P greatly promote the reduction of NO2- to NH3.

Facile preparation of Cu-Fe oxide nanoplates for ammonia borane decomposition and tandem nitroarene hydrogenation.

A facile substrate involved strategy was used to prepare Cu-Fe LDO (layered double oxide) nanoplates. The material exhibited good-efficiency for decomposition of ammonia borane (AB) in alkaline methanol solution. Significantly, the material also demonstrated excellent catalytic performance in the reduction of various nitroarenes by coupling with AB hydrolysis in a one pot tandem reaction, and gave excellent yields of the corresponding amine products.

Low energy consumption electrically regenerated ion-exchange for water desalination.

A new regeneration method of ion exchange resin named Adjacent Bed Electrically Regenerated Ion-exchange (ABERI) was proposed to eliminate the environmental impact of traditional chemical regeneration and improve the economy of replacing chemical regeneration with electrical regeneration. The desalting operation of ABERI was the same as the conventional mixed bed. When the resins were exhausted, anion and cation resins were separated and then packed in a dedicated regenerator adjacently. The resins were regenerated by the H+ and OH- ions produced from a pair of electrodes installed on both sides of the resin bed. By optimizing the regeneration time, current, and feed water flow rate, the energy consumption of ABERI was 0.38 kWh/m3 water; that is, 54% of that of another electrical regeneration technology, membrane-free electrodeionization (MFEDI). Compared with MFEDI, the quality and quantity of purified water produced after regeneration were improved. In ABERI, the average conductivity and the volume (times of bed volumes) of the purified water are 0.9 µS/cm and 109; that is, 75 and 133% of that of MFEDI, respectively. The preliminary economic analysis showed that ABERI offers the potential to regenerate ion exchange resin in an eco-friendly and cost-effective manner.

Visible light driven photo-reduction of Cu2+ to Cu2O to Cu in water for photocatalytic hydrogen production.

Metal nanoparticles are synthesized via various methods and have found many applications in areas such as sensing, electronics and catalysis. Light induced formation of noble metal nanoparticles, especially platinum, in solution or loaded on semiconductor surfaces, is an established practice in photocatalysis. Nevertheless, preparation of catalytically-active non-precious metal nanoparticles via photo-reduction still have room to be further explored. Here, we report a visible light driven system that can coordinate photo-reduction of CuSO4 to selectively prepare Cu2O or Cu nanoparticles, while at the same time, mediating efficient hydrogen production with in situ generating Cu catalyst without further need to add any components. The Cu2O and Cu nanoparticles in situ generated are crystalline in nature and can perform as pre-catalyst (Cu2O) or catalyst (Cu) to catalyze hydrogen production when reincorporated into the same photo-reduction system with organic photosensitizers. Our work offers an exploratory pathway to prepare target metal nanoparticles while provides some insight into harnessing solar energy for multi-functional purposes.

Highly flexible and stable carbon nitride/cellulose acetate porous films with enhanced photocatalytic activity for contaminants removal from wastewater.

This study describes the successful fabrication of flexible photocatalytic films to remove contaminants from wastewater, the film is comprising sulfuric acid treated graphitic carbon nitride (SA-g-C3N4) embedded within a porous cellulose network (denoted here as CN/CA films). The SA-g-C3N4 content in the films was varied from 0 to 50 wt.%. The sulfuric acid treatment introduced carboxyl and sulfonyl groups on the surface of g-C3N4, which resulted in strong hydrogen bonding with the hydroxyl groups of cellulose acetate (so strong the partial delimination of the SA-g-C3N4 occurred on CN/CA film formation via solvent casting). The obtained films were around 10 µm in thickness, extremely flexible and durable, with the SA-g-C3N4 uniformly distributed throughout the cellulose acetate network. The CN/CA films showed excellent activities for aqueous dye degradation under direct sunlight, as well as outstanding performance for photocatalytic reduction of Cr (VI). The photocatalytic activity of the CN/CA films at the optimum SA-g-C3N4 content of 50 wt.% was far higher than that of pristine SA-g-C3N4, highlighting a main advantage of the composite film fabrication strategy introduced here. Further, the CN/CA films showed excellent stability and reusability, with no loss in activity seen over 5 cycles of dye degradation.

Ir4+-Doped NiFe LDH to expedite hydrogen evolution kinetics as a Pt-like electrocatalyst for water splitting.

NiFe-layered double hydroxide (NiFe LDH) is a state-of-the-art oxygen evolution reaction (OER) electrocatalyst, yet it suffers from rather poor catalytic activity for the hydrogen evolution reaction (HER) due to its extremely sluggish water dissociation kinetics, severely restricting its application in overall water splitting. Herein, we report a novel strategy to expedite the HER kinetics of NiFe LDH by an Ir4+-doping strategy to accelerate the water dissociation process (Volmer step), and thus this catalyst exhibits superior and robust catalytic activity for finally oriented overall water splitting in 1 M KOH requiring only a low initial voltage of 1.41 V delivering at 20 mA cm-2 for more than 50 h.

Cu(OH)2 supported on Fe(OH)3 as a synergistic and highly efficient system for the dehydrogenation of ammonia-borane.

Herein, we first describe the physical mixture of Cu(OH)2/Fe(OH)3 as a composite catalyst precursor for the dehydrogenation of ammonia borane (AB) in methanol. During the initial period of catalytic reaction, Cu nanoparticles were formed in-situ. The catalytic activity of Cu nanoparticles can be significantly enhanced with the assistance of Fe species and OH-. A maximum turnover frequency (TOF) of 50.3 molH2 moltotal metal-1 min-1 (135.6 molH2 molCu-1 min-1) was achieved at ambient temperature, which is superior to those of previously reported Fe or Cu based systems.

Metal Phosphides as Co-Catalysts for Photocatalytic and Photoelectrocatalytic Water Splitting.

Solar-to-hydrogen conversion based on photocatalytic and photoelectrocatalytic water splitting is considered as a promising technology for sustainable hydrogen production. Developing earth-abundant H2 -production materials with robust activity and stability has become the mainstream in this field. Due to the unique properties and characteristics, transition metal phosphides (TMPs) have been proven to be high performance co-catalysts to replace some of the classic precious metal materials in photocatalytic water splitting. In this Minireview, we summarize the recent significant progress of TMPs as cocatalysts for water splitting reaction with high activity and stability. Firstly, the characteristic of TMPs is briefly introduced. Then, we mainly discuss the recent research efforts toward their application as photocatalytic co-catalysts in photocatalytic H2 -production, O2 -evolution and photoelectrochemical water splitting. Finally, the catalytic mechanism, current existing challenges and future working directions for improving the performance of TMPs are proposed.

Rapid synthesis of ultralong Fe(OH)3:Cu(OH)2 core-shell nanowires self-supported on copper foam as a highly efficient 3D electrode for water oxidation.

One-dimensional core-shell nanowire materials have recently received great attention as durable catalysts for water splitting. Herein we report the facile and rapid synthesis of ultralong Fe(OH)3:Cu(OH)2 core-shell nanowires grown in situ on an open 3D electrode to function as a highly efficient electrocatalyst for water oxidation. It only requires an overpotential of ∼365 mV to reach a 10 mA cm-2 current density in 1.0 M KOH. As far as we know, this shows the best result amongst Cu-based heterogeneous OER systems reported to date.

Self-Supported Cedarlike Semimetallic Cu3P Nanoarrays as a 3D High-Performance Janus Electrode for Both Oxygen and Hydrogen Evolution under Basic Conditions.

There has been strong and growing interest in the development of cost-effective and highly active oxygen evolution reaction (OER) electrocatalysts for alternative fuels utilization and conversion devices. We report herein that semimetallic Cu3P nanoarrays directly grown on 3D copper foam (CF) substrate can function as effective electrocatalysts for water oxidation. Specifically, the surface oxidation-activated Cu3P only required a relatively low overpotential of 412 mV to achieve a current density of 50 mA cm(-2) and displayed a small Tafel slope of 63 mV dec(-1) in 0.1 M KOH solution, on account of the collaborative effect of large roughness factor (RF) and semimetallic character. Following that, investigations into the mechanism revealed the formation of a unique active phase during the water oxidation process in which conductive Cu3P was the core covered with a thin copper oxide/hydroxide layer. Moreover, this Cu3P 3D electrode was also applied to the hydrogen evolution reaction (HER) and showed good catalytic performance and stability under the same basic conditions.

New platinum and ruthenium Schiff base complexes for water splitting reactions.

New platinum(ii) and ruthenium(ii) mononuclear complexes with naphthalene-based Schiff base ligands L1 (H2-selnaph) and L2 (H2-selnaph-COOH) were synthesized: Pt-selnaph (), Pt-selnaph-COOH (), Ru-selnaph(4-picoline)2 (), and Ru-selnaph(isoquinoline)2 (). The complexes were characterized by NMR spectroscopy, matrix-assisted laser desorption/ionization time-of-flight spectrometry, and elemental analysis, and their electrochemical and photophysical properties were investigated. The luminescent complexes and were used as photosensitizers for visible-light driven hydrogen production reactions in the presence of sacrificial electron donor triethylamine and cocatalyst precursor K2PtCl4 aqueous solution. When complex was attached to the surface of TiO2 by a carboxyl group, enhanced hydrogen photogeneration was achieved compared with complex alone, with turnover numbers of about 84 after 12 h irradiation. Calculations based on electrochemical and spectroscopic data also confirmed the feasibility of electron injection through the carboxyl group of complex into the conduction band of TiO2 for hydrogen production reactions. Complexes and were found to be efficient stable water oxidation (NH4)2Ce(NO3)6-driven catalysts with a first-order reaction behavior. A turnover frequency of 5.34 min(-1) was achieved for complex , while complex exhibited an enhanced turnover frequency of 11.9 min(-1) in pH 1.0 aqueous solution. Turnover numbers up to 1400 and 2060 were obtained after 6.5 h of reaction for and , respectively. Unique mechanistic information for water splitting is also presented through electrochemical, spectroscopic and ESI-MS high-valent ruthenium-oxo intermediate investigations.

Spectacular photocatalytic hydrogen evolution using metal-phosphide/CdS hybrid catalysts under sunlight irradiation.

A highly efficient and robust heterogeneous photocatalytic hydrogen evolution system was established for the first time by using the CoP/CdS hybrid catalyst in water under solar irradiation. The H2-production rate can reach up to 254,000 µmol h(-1) g(-1) during 4.5 h of sunlight irradiation, which is one of the highest values ever reported on CdS photocatalytic systems in the literature.

Photochemical, electrochemical, and photoelectrochemical water oxidation catalyzed by water-soluble mononuclear ruthenium complexes.

Two mononuclear ruthenium complexes [Ru(H2tcbp)(isoq)2] (1) and [Ru(H2tcbp)(pic)2] (2) (H4tcbp=4,4',6,6'-tetracarboxy-2,2'-bipyridine, isoq=isoquinoline, pic=4-picoline) are synthesized and fully characterized. Two spare carboxyl groups on the 4,4'-positions are introduced to enhance the solubility of 1 and 2 in water and to simultaneously allow them to tether to the electrode surface by an ester linkage. The photochemical, electrochemical, and photoelectrochemical water oxidation performance of 1 in neutral aqueous solution is investigated. Under electrochemical conditions, water oxidation is conducted on the deposited indium-tin-oxide anode, and a turnover number higher than 15,000 per water oxidation catalyst (WOC) 1 is obtained during 10 h of electrolysis under 1.42 V vs. NHE, corresponding to a turnover frequency of 0.41 s(-1). The low overpotential (0.17 V) of electrochemical water oxidation for 1 in the homogeneous solution enables water oxidation under visible light by using [Ru(bpy)3](2+) (P1) (bpy=2,2'-bipyridine) or [Ru(bpy)2(4,4'-(COOEt)2-bpy)](2+) (P2) as a photosensitizer. In a three-component system containing 1 or 2 as a light-driven WOC, P1 or P2 as a photosensitizer, and Na2S2O8 or [CoCl(NH3)5]Cl2 as a sacrificial electron acceptor, a high turnover frequency of 0.81 s(-1) and a turnover number of up to 600 for 1 under different catalytic conditions are achieved. In a photoelectrochemical system, the WOC 1 and photosensitizer are immobilized together on the photoanode. The electrons efficiently transfer from the WOC to the photogenerated oxidizing photosensitizer, and a high photocurrent density of 85 µA cm(-2) is obtained by applying 0.3 V bias vs. NHE.