Accurate Boron Determination in Tourmaline by Inductively Coupled Plasma Mass Spectrometry: An Insight into the Boron-Mannitol Complex-Based Wet Acid Digestion Method.

Tourmaline, a boron-bearing mineral, has been extensively applied as a geothermometer, provenance indicator, and fluid-composition recorder in geological studies. In this paper, the decomposition capability of an HF-HNO3-mannitol mixture for a tourmaline sample was investigated in detail for the first time, and a wet acid digestion method based on the boron-mannitol complex for accurate boron determination in tourmaline by inductively coupled plasma mass spectrometry (ICP-MS) was proposed. With a digestion temperature of 140 °C, tourmaline samples of 25 mg (±0.5 mg) can be completely decomposed by a ternary mixture, which consisted of 0.6 mL of HF, 0.6 mL of HNO3, and 0.7 mL of 2% mannitol (wt.), via a continuous heating treatment of 36 h. Following gentle evaporation at 100 °C, the sample residues were re-dissolved using 2 mL of 40% HNO3 solution (wt.) and diluted to about 2.0 × 105-fold by a two-step method using 2% HNO3 solution (wt.). The boron contents in a batch of parallel tourmaline samples were then determined by ICP-MS, and results showed that the boron concentration levels were in a range of 3.20-3.44% with determination RSDs less than 4.0% (n = 5). It was found that the boron concentrations obtained at the mass of 10B were comparable with results from the measurements at the mass of 11B. This revealed that the usage of 2% mannitol with a quantity as high as 0.7 mL in this developed approach did not exhibit significant effect on the quantification accuracy of boron at the mass of 11B. It was also found that the processes including fluoride-forming prevention and fluoride decomposition deteriorated the boron-reserving efficiency of mannitol for tourmaline, causing the averaged boron contents to vary from 2.25% to 3.57% (n = 5). Furthermore, the stability of the boron-mannitol complex under 185 °C by applying the laboratory high pressure-closed digestion method was evaluated, which showed that there existed a 60.36% loss of boron compared to that under 140 °C by using this proposed approach. For this ternary mixture, the tourmaline decomposing efficiency was found to be weakened prominently using 100 °C as the digestion temperature, and tourmaline powders can be observed even after 72 h of continuous heating with B contents within 1.09-1.23% (n = 5). To assess the accuracy of this developed method, the boron recovery of anhydrous lithium tetraborate was studied. It was found that the boron recoveries were within 96.59-102.12% (RSD < 1%, n = 5), demonstrating the accuracy and reliability of this proposed method, which exhibits advantages of high B preserving efficiency, and giving concentration information of both B and trace elements simultaneously. By applying such a boron-mannitol complex-based wet acid digestion method, the chemical composition of boron and trace elements in three tourmaline samples from different pegmatites were quantified, which provided valuable information to distinguish regional deposits and the associated evolution stages.

In-Depth Method Investigation for Determination of Boron in Silicate Samples Using an Improved Boron-Mannitol Complex Digestion Method by Inductively Coupled Plasma Mass Spectrometry.

In this paper, a boron-mannitol complex wet acid digestion method proposed for the accurate determination of boron in silicate samples by inductively coupled plasma mass spectrometry (ICP-MS) was investigated in detail for the first time. With the addition of 50 µL of mannitol (2% wt.) into the mixture of 0.6 mL of concentrated HF and 30 µL of concentrated HNO3, the 50 mg of silicate sample was effectively decomposed after being heated overnight with optional pre-ultrasonic treatment. Following fluoride formation prevention by 8% HNO3 (wt.) and fluoride decomposition using 6% HCl (wt.), the samples were fluxed in 2.0 mL of 40% HNO3 (wt.) for 4 h and aged overnight. By diluting 1000-fold using 2% HNO3 (wt.) solution, the samples were directly quantified by an ICP-MS, showing boron recoveries of the standard materials including diabase W-2, basalt JB-2a, and rhyolite JR-2 in the range of 95.5-105.5% (n = 5). For this wet acid method, it was found that the contents of boron had no obvious difference under digestion temperatures of 65, 100, and 140 °C. It was also found that the ICP-MS quantification accuracy deteriorated at the mass of 11B when boron content was about 7250 ng yielding positive bias with average recoveries of 115.5-119.8% (n = 5), while the determination results remained unaffected at the mass of 10B. Furthermore, the digestion efficiency of boron by laboratory high-pressure closed digestion method was assessed. The boron recoveries with samples treated by the high-pressure closed digestion method were found to vary within 49.5-98.0% (n = 5) and even lowered down to 31.1% when skipping pressure relief procedure. The long-term quantification stability study showed that the boron content generally declined in one month for the high-pressure closed digestion method and exhibited no significant changes for the proposed method. By applying such an improved boron-mannitol complex digestion method, the boron concentration in the studied silicate standard materials were accurately determined, providing critical data for further boron isotope analyses and associated geochemical studies. This in-depth method investigation for silicate boron determination demonstrates the feasibility of this boron-mannitol complex strategy under a wide digestion temperature of 65-140 °C, and also sheds light on the extensive applications of boron as a geological tracer.

Phase-Controlled Synthesis of Pd-Se Nanocrystals for Phase-Dependent Oxygen Reduction Catalysis.

Searching for highly efficient oxygen reduction reaction (ORR) electrocatalysts for fuel cell technology, in which the crystal structure plays a powerful role in regulating the electrocatalysis, is urgent yet challenging. Herein, we have explored the active and stable Pd-Se alloy electrocatalysts with controlled phase toward alkaline ORR. The phase-controlled Pd-Se nanoparticles (NPs) show interesting phase-dependent electrocatalytic performance, in which the Pd17Se15 NPs/C exhibits much better ORR performance than its counterpart, Pd7Se4 NPs/C, and the commercial Pd/C and Pt/C. Based on the detailed analysis, Pd in Pd17Se15 possesses more Se atom coordination and a higher valence state, thus providing a stronger capacity for the absorption of oxygenated species. DFT further reveals more charge transfer from the Pd17Se15 surface to the *OOH intermediate, which is the reason for the activity enhancement.

Highly Surface-Distorted Pt Superstructures for Multifunctional Electrocatalysis.

Platinum (Pt) catalysts play a key role in energy conversion and storage processes, but the realization of further performance enhancement remains challenging. Herein, we report a new class of Pt superstructures (SSs) with surface distortion engineering by electrochemical leaching of PtTex SSs that can largely boost the oxygen reduction reaction (ORR), the methanol oxidation reaction (MOR), and the hydrogen evolution reaction (HER). In particular, the high-distortion (H)-Pt SSs achieve a mass activity of 2.24 A mg-1 at 0.90 VRHE for the ORR and 2.89 A mg-1 for the MOR as well as a low overpotential of 25.3 mV at 10 mA cm-2 for the HER. Moreover, the distorted surface features of Pt SSs can be preserved by mitigating the detrimental effects of agglomeration/degradation during long-time electrocatalysis. A multiscale modeling demonstrates that surface compressions, defects, and nanopores act in synergy for the enhanced ORR performance. This work highlights the advances of stable superstructure and distortion engineering for realizing high-performance Pt nanostructures.

Te-Doped Pd Nanocrystal for Electrochemical Urea Production by Efficiently Coupling Carbon Dioxide Reduction with Nitrite Reduction.

The renewable electricity-driven reduction of carbon dioxide (CO2RR) is a promising technology for carbon utilization. However, it is still a challenge to broaden the application of CO2RR. Herein, we report a Te-doped Pd nanocrystals (Te-Pd NCs) for promoting urea synthesis by coupling CO2RR with electrochemical reduction of nitrite. The electrochemical synthesis of urea has been achieved with nearly 12.2% Faraday efficiency (FE) and 88.7% N atom efficiency (NE) at -1.1 V versus reversible hydrogen electrode (vs RHE), much higher than those of pure Pd NCs (4.2% FE and 21.8% NE). Significantly, an FE of ∼10.2% and an NE of ∼82.3% for urea solution production via an optimized flow cell system have been realized, where a solution with up to 0.95 wt % of urea has been obtained. Mechanistic insights show that Te-doping not only optimizes the CO2/CO adsorption but also promotes NH3 production, fully meeting the requirements of urea synthesis.

On-Demand, Ultraselective Hydrogenation System Enabled by Precisely Modulated Pd-Cd Nanocubes.

The pursuit of efficient hydrogenation nanocatalysts with a desirable selectivity toward intricate substrates is state-of-the-art research but remains a formidable challenge. Herein, we report a series of novel PdCdx nanocubes (NCs) for ultraselective hydrogenation reactions with flexible tuning features. Obtaining a desirable conversion level of the substrates (e.g., 4-nitrophenylacetylene (NPA), 4-nitrobenzaldehyde (NBAD), and 4-nitrostyrene (NS)) and competitive selectivity for all potential hydrogenation products have been achieved one by one under optimized hydrogenation conditions. The performance of these PdCdx NCs displays an evident dependence on both the composition and the use of Cd and a need for a distinct hydrogen source (H2 or HCOONH4). Additionally, for the selectivity of hydrogen to be suitably high, the morphology of the NCs has a very well-defined effect. Density functional theory calculations confirmed the variation of adsorption energy for the substrate and hydrogenation products by carefully controlled introduction of Cd, leading to a desirable level of selectivity for all potential hydrogenation products. The PdCdx NCs also exhibit excellent reusability with negligible activity/selectivity decay and structural/composition changes after consecutive reactions. The present study provides an advanced strategy for the rational design of superior hydrogenation nanocatalysts to achieve a practical application for desirable and selective hydrogenation reaction efficiency.

Defect Engineering of Palladium-Tin Nanowires Enables Efficient Electrocatalysts for Fuel Cell Reactions.

The defect engineering of noble metal nanostructures is of vital importance because it can provide an additional yet advanced tier to further boost catalysis, especially for one-dimensional (1D) noble metal nanostructures with a high surface to bulk ratio and more importantly the ability to engineer the defect along the longitudinal direction of the 1D nanostructures. Herein, for the first time, we report that the defect in 1D noble metal nanostructures is a largely unrevealed yet essential factor in achieving highly active and stable electrocatalysts toward fuel cell reactions. The detailed electrocatalytic results show that the Pd-Sn nanowires (NWs) exhibit interesting defect-dependent performance, in which the defect-rich Pd4Sn wavy NWs display the highest activity and durability for both the methanol oxidation reaction (MOR) and the oxygen reduction reaction (ORR). Density functional theory (DFT) calculations reveal that a large number of surface vacancies/agglomerated voids are the driving forces for forming surface grain boundaries (GBs) within Pd4Sn WNWs. These electronic active GB regions are the key factors in preserving the number of Pd0 sites, which are critical for minimizing the intrinsic site-to-site electron-transfer barriers. Through this defect engineering, the Pd4Sn WNWs ultimately yield highly efficient alkaline ORR and MOR. The present work highlights the importance of defect engineering in boosting the performance of electrocatalysts for potentially practical fuel cells and energy applications.

Partially Pyrolyzed Binary Metal-Organic Framework Nanosheets for Efficient Electrochemical Hydrogen Peroxide Synthesis.

Herein, we developed a partially controlled pyrolysis strategy to create evenly distributed NiO nanoparticles within NiFe-MOF nanosheets (MOF NSs) for electrochemical synthesis of H2 O2 by a two-electron oxygen reduction reaction (ORR). The elemental Ni can be partially transformed to NiO and uniformly distributed on the surface of the MOF NSs, which is crucial for the formation of the particular structure. The optimized MOF NSs-300 exhibits the highest activity for ORR with near-zero overpotential and excellent H2 O2 selectivity (ca. 99 %) in 0.1 m KOH solution. A high-yield H2 O2 production rate of 6.5 mol gcat -1 h-1 has also been achieved by MOF NSs-300 in 0.1 m KOH and at 0.6 V (vs. RHE). In contrast to completely pyrolyzed products, the enhanced catalytic activities of partially pyrolyzed MOF NSs-300 originates mainly from the retained MOF structure and the newly generated NiO nanoparticles, forming the coordinatively unsaturated Ni atoms and tuning the performance towards electrochemical H2 O2 synthesis.

Promoting the Direct H2 O2 Generation Catalysis by Using Hollow Pd-Sn Intermetallic Nanoparticles.

Although direct hydrogen (H2 ) oxidation to hydrogen peroxide (H2 O2 ) is considered as a promising strategy for direct H2 O2 synthesis, the desirable conversion efficiency remains formidable challenge. Herein, highly active and selective direct H2 oxidation to H2 O2 is achieved by using hollow Pd-Sn intermetallic nanoparticles (NPs) as the catalysts. By tuning the catalytic solvents and catalyst supports, the efficiency of direct H2 oxidation to H2 O2 can be optimized well with the hollow Pd2 Sn NPs/P25 exhibiting H2 O2 selectivity up to 80.7% and productivity of 60.8 mol kgcat-1 h-1 . In situ diffuse reflectance infrared Fourier transform spectroscopy of CO adsorption results confirm the different surface atom arrangements between solid and hollow Pd-Sn NPs. X-ray photoelectron spectra results show that the higher efficiency of Pd2 Sn NPs/P25 is due to its higher content of metallic Pd and higher ratio of Snx+ , which benefit H2 O2 production and selectivity.

Highly Efficient Carbon Dioxide Hydrogenation to Methanol Catalyzed by Zigzag Platinum-Cobalt Nanowires.

Carbon dioxide (CO2 ) hydrogenation is an effective strategy for CO2 utilization, while unsatisfied conversion efficiencies remain great challenges. It is reported herein that zigzag Pt-Co nanowires (NWs) with Pt-rich surfaces and abundant steps/edges can perform as highly active and stable CO2 hydrogenation catalysts. It is found that tuning the Pt/Co ratio of the Pt-Co NWs, solvents, and catalyst supports could well optimize the CO2 hydrogenation to methanol (CH3 OH) with the Pt4 Co NWs/C exhibiting the best performance, outperforming all the previous catalysts. They are also very durable with limited activity decays after six catalytic cycles. The diffuse reflectance infrared Fourier transform spectroscopy result of CO2 adsorption shows that the Pt4 Co NWs/C undergoes the adsorption/activation of CO2 by forming appropriate carboxylate intermediates, and thus enhancing the CH3 OH production.

Ordered macroporous quercetin molecularly imprinted polymers: Preparation, characterization, and separation performance.

Ordered macroporous molecularly imprinted polymers were prepared by a combination of the colloidal crystal templating method and the molecular imprinting technique by using SiO2 colloidal crystal as the macroporogen, quercetin as the imprinting template, acrylamide as the functional monomer, ethylene glycol dimethacrylate as the cross-linker and tetrahydrofuran as the solvent. Scanning electron microscopy and Brunauer-Emmett-Teller measurements show that the ordered macroporous molecularly imprinted polymers have a more regular macroporous structure, a narrower pore distribution and a greater porosity compared with the traditional bulk molecularly imprinted polymers. The kinetic and isothermal adsorption behaviors of the polymers were investigated. The results indicate that the ordered macroporous molecularly imprinted polymers have a faster intraparticle mass transfer process and a higher adsorption capacity than the traditional bulk molecularly imprinted polymers. The ordered macroporous molecularly imprinted polymers were further employed as a sorbent for a solid-phase extraction. The results show that the ordered macroporous molecularly imprinted polymers can effectively separate quercetin from the Gingko hydrolysate.

3D Platinum-Lead Nanowire Networks as Highly Efficient Ethylene Glycol Oxidation Electrocatalysts.

A large-scalable wet-chemical approach to create networked Pt-Pb nanowires (NWs) with tunable compositions is reported. Due to their 3D networked structure, alloy effect, rich defects/steps, and antipoisoning property of Pb, the networked Pt-Pb NWs exhibit the best activity and durability towards ethylene glycol oxidation reaction (EGOR), compared with the networked Pt NWs and Pt/C.

MicroRNAs used as novel biomarkers for detecting cancer metastasis.

The low survival rates of cancers are primarily due to late diagnosis and metastasis. Discriminating the metastasis is a crucial factor for prognosis and improving the survival rate of cancer patients. MicroRNAs (miRNAs) can regulate the expression of hundreds of downstream genes, which has a broad effect on the regulation of the whole cell cycle. Accumulating studies have found that the aberrant expression of miRNAs is associated with cancer genesis. The aim of this study is to evaluate the diagnostic value of miRNAs in detecting cancer metastasis. Medline, PubMed, Embase, and CNKI were searched for relevant articles. Sensitivity, specificity, positive and negative likelihood ratio (PLR, NLR) and diagnostic odds ratio (DOR), the summary receiver operator characteristic (SROC) curve and the calculated AUC (area under the SROC curve) were applied to explore the diagnostic accuracy of miRNAs in metastasis. Seven hundred seventy-one metastatic cancer patients and 552 non-metastatic cancer controls from 14 articles were involved in our meta-analysis. A sensitivity of 0.75 (95% confidence interval (CI), 0.72-0.79) and a specificity of 0.80 (95% CI, 0.76-0.84) were observed from metastatic patients and non-metastatic controls in the combined analysis. And the AUC was 0.83 (95% CI, 0.79-0.86). In addition, results from subgroup analyses suggested that a higher diagnostic value for metastasis was acquired in tissue sample other than blood sample (sensitivity, 0.82 versus 0.73; specificity, 0.84 versus 0.79; PLR, 5.0 versus 3.5; NLR, 0.22 versus 0.34; DOR, 23 versus 10; AUC, 0.88 versus 0.80). In summary, this meta-analysis proved the relatively high diagnostic value of miRNA in metastasis, which might be applied as a novel screening tool to detect metastasis along with other biomarkers. We also illustrated that tissue-based miRNAs may have a better diagnostic accuracy than blood-based miRNAs.

Separation and characterization of sucrose esters from Oriental tobacco leaves using accelerated solvent extraction followed by SPE coupled to HPLC with ion-trap MS detection.

Sucrose esters (SEs) were successfully extracted from Oriental tobacco leaves using a new methodology based on accelerated solvent extraction followed by hydrophilic-lipophilic balanced cartridge cleanup step. The SEs were detected by HPLC with ion-trap MS detection using an electrospray interface operated in the positive ion mode. This methodology combines the high efficiency of extraction provided by a pressurized fluid and the highly sensitive characterization offered by ion-trap MS. Under the optimized conditions, 14 SEs were first identified among a total of 23 SEs found in Oriental tobacco leaves. Under the same conditions, only four new SEs were extracted by using traditional ultrasound-assisted extraction and liquid-solid extraction methods. The present method might be potentially useful in high-efficiency extraction and sensitive characterization of SEs from complex matrices such as tobacco leaves.

Clinical application of VATS combined with 3D-CTBA in anatomical basal segmentectomy.

Objective: This study aimed to summarize the clinical application experience of video-assisted thoracic surgery (VATS) combined with three-dimensional computed tomography-bronchography and angiography (3D-CTBA) in anatomical basal segmentectomy. Methods: Clinical data of 42 patients who underwent bilateral lower sub-basal segmentectomy by VATS combined with 3D-CTBA in our hospital from January 2020 to June 2022 were retrospectively analyzed; the patients included 20 males and 22 females, with a median age of 48 (30-65) years. Combined with the preoperative enhanced CT and 3D-CTBA techniques to identify the altered bronchi, arteries, and veins during the operation, the anatomical resection of each basal segment of both lower lungs was completed through the fissure approach or inferior pulmonary vein approach. Results: All operations were successfully completed without conversion to thoracotomy or lobectomy. The median operation time was 125 (90-176) min, the median intraoperative blood loss was 15 (10-50) mL, the median postoperative thoracic drainage time was 3 (2-17) days, and the median postoperative hospital stay was 5 (3-20) days. The median number of resected lymph nodes was 6 (5-8). There was no in-hospital death. Postoperative pulmonary infection occurred in 1 case, lower extremity deep vein thrombosis (DVT) in 3 cases, pulmonary embolism in 1 case, and persistent air leakage in the chest in 5 cases, all of which were improved by conservative treatment. Two cases of pleural effusion after discharge were improved after ultrasound guided drainage. Postoperative pathology showed 31 cases of minimally invasive adenocarcinoma, 6 cases of adenocarcinoma in situ (AIS), 3 cases of severe atypical adenomatous hyperplasia (AAH), and 2 cases of other benign nodules. All cases were lymph node-negative. Conclusion: VATS combined with 3D-CTBA is safe and feasible in anatomical basal segmentectomy; consequently, this approach should be promoted and applied in clinical work.

The relationship between cyber upward social comparison and cyberbullying behaviors: A moderated mediating model.

Based on the General Strain Theory and the moderating role model of social support, the present study explored the relationship between cyber upward social comparison and cyberbullying and further explored the mediating role of moral justification and the moderating role of online social support. This model was examined with 660 Chinese college students. Participants completed questionnaires regarding cyber upward social comparison, cyberbullying, moral justification, and online social support. After basic demographic variables were controlled, cyber upward social comparison was significantly and positively associated with cyberbullying. Moral justification played a mediating role in the relationship between cyber upward social comparison and cyberbullying. The mediating effect of moral justification on the relationship between cyber upward social comparison and cyberbullying was moderated by online social support. The results of this study will provide references for the prevention and intervention of cyberbullying.

Rhombohedral Pd-Sb Nanoplates with Pd-Terminated Surface: An Efficient Bifunctional Fuel-Cell Catalyst.

Developing high-performance electrocatalysts for the ethanol oxidation reaction (EOR) and the oxygen reduction reaction (ORR) is essential for the commercialization of direct ethanol fuel cells, but it is still formidably challenging. In this work, a novel Pd-Sb hexagonal nanoplate for boosting both cathodic and anodic fuel cell reactions is prepared. Detailed characterizations reveal that the nanoplates have ordered rhombohedral phase of Pd8 Sb3 (denoted as Pd8 Sb3 HPs). The Pd8 Sb3 HPs exhibit much enhanced activity toward the oxidation of various alcohols. Particularly, Pd8 Sb3 HPs/C displays superior specific and mass activities of 29.3 mA cm-2 and 4.5 A mgPd -1 toward the EOR, which are 7.0 and 11.3 times higher than those of commercial Pd/C, and 9.8 and 3.8 times higher than those of commercial Pt/C, respectively, representing one of the best EOR catalysts reported to date. In situ electrochemical attenuated total reflectance surface-enhanced infrared absorption spectroscopy (ATR-SEIRAS) measurements reveal that Pd8 Sb3 HPs/C can effectively promote the C2 pathway of the EOR. As revealed by density functional theory calculations, the high EOR activity of the Pd8 Sb3 HPs can be ascribed to the reduced energy barrier of ethanol dehydrogenation. Additionally, Pd8 Sb3 HPs/C also shows superior performance in the ORR. This work advances the controllable synthesis of the Pd-Sb nanostructure, giving huge impetus for the design of high-efficiency electrocatalysts for energy conversion and beyond.

Subnanometer high-entropy alloy nanowires enable remarkable hydrogen oxidation catalysis.

High-entropy alloys (HEAs) with unique physicochemical properties have attracted tremendous attention in many fields, yet the precise control on dimension and morphology at atomic level remains formidable challenges. Herein, we synthesize unique PtRuNiCoFeMo HEA subnanometer nanowires (SNWs) for alkaline hydrogen oxidation reaction (HOR). The mass and specific activities of HEA SNWs/C reach 6.75 A mgPt+Ru-1 and 8.96 mA cm-2, respectively, which are 2.8/2.6, 4.1/2.4, and 19.8/18.7 times higher than those of HEA NPs/C, commercial PtRu/C and Pt/C, respectively. It can even display enhanced resistance to CO poisoning during HOR in the presence of 1000 ppm CO. Density functional theory calculations reveal that the strong interactions between different metal sites in HEA SNWs can greatly regulate the binding strength of proton and hydroxyl, and therefore enhances the HOR activity. This work not only provides a viable synthetic route for the fabrication of Pt-based HEA subnano/nano materials, but also promotes the fundamental researches on catalysis and beyond.

Atomically Isolated Rh Sites within Highly Branched Rh2 Sb Nanostructures Enhance Bifunctional Hydrogen Electrocatalysis.

Breaking the bottleneck of hydrogen oxidation/evolution reactions (HOR/HER) in alkaline media is of tremendous importance for the development of anion exchange membrane fuel cells/water electrolyzers. Atomically dispersed active sites are known to exhibit excellent activity and selectivity toward diverse catalytic reactions. Here, a class of unique Rh2 Sb nanocrystals with multiple nanobranches (denoted as Rh2 Sb NBs) and atomically dispersed Rh sites are reported as promising electrocatalysts for alkaline HOR/HER. Rh2 Sb NBs/C exhibits superior HER performance with a low overpotential and a small Tafel slope, outperforming both Rh NBs/C and commercial Pt/C. Significantly, Rh2 Sb NBs show outstanding HOR performance of which the HOR specific activity and mass activity are about 9.9 and 10.1 times to those of Rh NBs/C, and about 4.2 and 3.7 times to those of Pt/C, respectively. Strikingly, Rh2 Sb NBs can also exhibit excellent CO tolerance during HOR, whose activity can be largely maintained even at 100 ppm CO impurity. Density functional theory calculations reveal that the unsaturated Rh sites on Rh2 Sb NBs surface are crucial for the enhanced alkaline HER and HOR activities. This work provides a unique catalyst design for efficient hydrogen electrocatalysis, which is critical for the development of alkaline fuel cells and beyond.

A Generalized Surface Chalcogenation Strategy for Boosting the Electrochemical N2 Fixation of Metal Nanocrystals.

Electrocatalytic nitrogen reduction reaction (NRR) is a promising process relative to energy-intensive Haber-Bosch process. While conventional electrocatalysts underperform with sluggish paths, achieving dissociation of N2 brings the key challenge for enhancing NRR. This study proposes an effective surface chalcogenation strategy to improve the NRR performance of pristine metal nanocrystals (NCs). Surprisingly, the NH3 yield and Faraday efficiency (FE) (175.6 ± 23.6 mg h-1 g-1 Rh and 13.3 ± 0.4%) of Rh-Se NCs is significantly enhanced by 16 and 15 times, respectively. Detailed investigations show that the superior activity and high FE are attributed to the effect of surface chalcogenation, which not only can decrease the apparent activation energy, but also inhibit the occurrence of the hydrogen evolution reaction (HER) process. Theoretical calculations reveal that the strong interface strain effect within core@shell system induces a critical redox inversion, resulting in a rather low valence state of Rh and Se surface sites. Such strong correlation indicates an efficient electron-transfer minimizing NRR barrier. Significantly, the surface chalcogenation strategy is general, which can extend to create other NRR metal electrocatalysts with enhanced performance. This strategy open a new avenue for future NH3 production for breakthrough in the bottleneck of NRR.