Facet-switching of rate-determining step on copper in CO2-to-ethylene electroreduction.

Reduction of carbon dioxide (CO2) by renewable electricity to produce multicarbon chemicals, such as ethylene (C2H4), continues to be a challenge because of insufficient Faradaic efficiency, low production rates, and complex mechanistic pathways. Here, we report that the rate-determining steps (RDS) on common copper (Cu) surfaces diverge in CO2 electroreduction, leading to distinct catalytic performances. Through a combination of experimental and computational studies, we reveal that C─C bond-making is the RDS on Cu(100), whereas the protonation of *CO with adsorbed water becomes rate-limiting on Cu(111) with a higher energy barrier. On an oxide-derived Cu(100)-dominant Cu catalyst, we reach a high C2H4 Faradaic efficiency of 72%, partial current density of 359 mA cm-2, and long-term stability exceeding 100 h at 500 mA cm-2, greatly outperforming its Cu(111)-rich counterpart. We further demonstrate constant C2H4 selectivity of >60% over 70 h in a membrane electrode assembly electrolyzer with a full-cell energy efficiency of 23.4%.

Efficient and stable acidic CO2 electrolysis to formic acid by a reservoir structure design.

Electrochemical synthesis of valuable chemicals and feedstocks through carbon dioxide (CO2) reduction in acidic electrolytes can surmount the considerable CO2 loss in alkaline and neutral conditions. However, achieving high productivity, while operating steadily in acidic electrolytes, remains a big challenge owing to the severe competing hydrogen evolution reaction. Here, we show that vertically grown bismuth nanosheets on a gas-diffusion layer can create numerous cavities as electrolyte reservoirs, which confine in situ-generated hydroxide and potassium ions and limit inward proton diffusion, producing locally alkaline environments. Based on this design, we achieve formic acid Faradaic efficiency of 96.3% and partial current density of 471 mA cm-2 at pH 2. When operated in a slim continuous-flow electrolyzer, the system exhibits a full-cell formic acid energy efficiency of 40% and a single pass carbon efficiency of 79% and performs steadily over 50 h. We further demonstrate the production of pure formic acid aqueous solution with a concentration of 4.2 weight %.

Porous Tellurium-Doped Ruthenium Dioxide Nanotubes for Enhanced Acidic Water Oxidation.

Electrocatalysts with high activity and durability for acidic oxygen evolution reaction (OER) play a crucial role in achieving cost-effective hydrogen production via proton exchange membrane water electrolysis. A novel electrocatalyst, Te-doped RuO2 (Te-RuO2) nanotubes, synthesized using a template-directed process, which significantly enhances the OER performance in acidic media is reported. The Te-RuO2 nanotubes exhibit remarkable OER activity in acidic media, requiring an overpotential of only 171 mV to achieve an anodic current density of 10 mA cm-2. Furthermore, they maintain stable chronopotentiometric performance under 10 mA cm-2 in acidic media for up to 50 h. Based on the experimental results and density functional calculations, this significant improvement in OER performance to the synergistic effect of large specific surface area and modulated electronic structure resulting from the doping of Te cations is attributed.

Plasma-Assisted Synthesis of Metal Nitrides for an Efficient Platinum-Group-Metal-Free Anion-Exchange-Membrane Fuel Cell.

In comparison to the well-developed proton-exchange-membrane fuel cells, anion-exchange-membrane fuel cells (AEMFCs) permit adoption of platinum-group-metal (PGM)-free catalysts due to the alkaline environment, giving a substantial cost reduction. However, previous AEMFCs have generally shown unsatisfactory performances due to the lack of effective PGM-free catalysts that can endure harsh fuel cell conditions. Here we report a plasma-assisted synthesis of high-quality nickel nitride (Ni3N) and zirconium nitride (ZrN) employing dinitrogen as the nitrogen resource, exhibiting exceptional catalytic performances toward hydrogen oxidation and oxygen reduction in an alkaline enviroment, respectively. A PGM-free AEMFC assembled by using Ni3N as the anode and ZrN as the cathode delivers power densities of 256 mW cm-2 under an H2-O2 condition and 151 mW cm-2 under an H2-air condition. Furthermore, the fuel cell shows no evidence of degradation after 25 h of operation. This work creates opportunities for developing high-performance and durable AEMFCs based on metal nitrides.

Mn-Incorporation-Induced Phase Transition in Bottom-Up Synthesized Colloidal Sub-1-nm Ni(OH)2 Nanosheets for Enhanced Oxygen Evolution Catalysis.

Sub-1-nm structures are attractive for diverse applications owing to their unique properties compared to those of conventional nanomaterials. Transition-metal hydroxides are promising catalysts for oxygen evolution reaction (OER), yet there remains difficulty in directly fabricating these materials within the sub-1-nm regime, and the realization of their composition and phase tuning is even more challenging. Here we define a binary-soft-template-mediated colloidal synthesis of phase-selective Ni(OH)2 ultrathin nanosheets (UNSs) with 0.9 nm thickness induced by Mn incorporation. The synergistic interplay between binary components of the soft template is crucial to their formation. The unsaturated coordination environment and favorable electronic structures of these UNSs, together with in situ phase transition and active site evolution confined by the ultrathin framework, enable efficient and robust OER electrocatalysis. They exhibit a low overpotential of 309 mV at 100 mA cm-2 as well as remarkable long-term stability, representing one of the most high-performance noble-metal-free catalysts.

Unraveling Stoichiometry Effect in Nickel-Tungsten Alloys for Efficient Hydrogen Oxidation Catalysis in Alkaline Electrolytes.

Anion-exchange membrane fuel cells provide the possibility to use platinum group metal-free catalysts, but the anodic hydrogen oxidation reaction (HOR) suffers from sluggish kinetics and its source is still debated. Here, over nickel-tungsten (Ni-W) alloy catalysts, we show that the Ni : W ratio greatly governs the HOR performance in alkaline electrolyte. Experimental and theoretical studies unravel that alloying with W can tune the unpaired electrons in Ni, tailoring the potential of zero charge and the catalytic surface to favor hydroxyl adsorption (OHad). The OHad species coordinately interact with potassium (K+) ions, which break the K+ solvation sheath to leave free water molecules, yielding an improved connectivity of hydrogen-bond networks. Consequently, the optimal Ni17W3 alloy exhibits alkaline HOR activity superior to the state-of-the-art platinum on carbon (Pt/C) catalyst and operates steadily with negligible decay after 10,000 cycles. Our findings offer new understandings of alloyed HOR catalysts and will guide rational design of next-generation catalysts for fuel cells.

Efficient NH3-Tolerant Nickel-Based Hydrogen Oxidation Catalyst for Anion Exchange Membrane Fuel Cells.

Converting hydrogen chemical energy into electrical energy by fuel cells offers high efficiencies and environmental advantages, but ultrapure hydrogen (over 99.97%) is required; otherwise, the electrode catalysts, typically platinum on carbon (Pt/C), will be poisoned by impurity gases such as ammonia (NH3). Here we demonstrate remarkable NH3 resistivity over a nickel-molybdenum alloy (MoNi4) modulated by chromium (Cr) dopants. The resultant Cr-MoNi4 exhibits high activity toward alkaline hydrogen oxidation and can undergo 10,000 cycles without apparent activity decay in the presence of 2 ppm of NH3. Furthermore, a fuel cell assembled with this catalyst retains 95% of the initial peak power density even when NH3 (10 ppm)/H2 was fed, whereas the power output reduces to 61% of the initial value for the Pt/C catalyst. Experimental and theoretical studies reveal that the Cr modifier not only creates electron-rich states that restrain lone-pair electron donation but also downshifts the d-band center to suppress d-electron back-donation, synergistically weakening NH3 adsorption.

Highly Enhanced Chloride Adsorption Mediates Efficient Neutral CO2 Electroreduction over a Dual-Phase Copper Catalyst.

Electrocatalytic carbon dioxide reduction (CO2R) in neutral electrolytes can mitigate the energy and carbon losses caused by carbonate formation but often experiences unsatisfied multicarbon selectivity and reaction rates because of the kinetic limitation to the critical carbon monoxide (CO)-CO coupling step. Here, we describe that a dual-phase copper-based catalyst with abundant Cu(I) sites at the amorphous-nanocrystalline interfaces, which is electrochemically robust in reducing environments, can enhance chloride-specific adsorption and consequently mediate local *CO coverage for improved CO-CO coupling kinetics. Using this catalyst design strategy, we demonstrate efficient multicarbon production from CO2R in a neutral potassium chloride electrolyte (pH ∼6.6) with a high Faradaic efficiency of 81% and a partial current density of 322 milliamperes per square centimeter. This catalyst is stable after 45 h of operation at current densities relevant to commercial CO2 electrolysis (300 mA per square centimeter).

Gerhardtite as a Precursor to an Efficient CO-to-Acetate Electroreduction Catalyst.

Carbon-carbon coupling electrochemistry on a conventional copper (Cu) catalyst still undergoes low selectivity among many different multicarbon (C2+) chemicals, posing a grand challenge to achieve a single C2+ product. Here, we demonstrate a laser irradiation synthesis of a gerhardtite mineral, Cu2(OH)3NO3, as a catalyst precursor to make a Cu catalyst with abundant stacking faults under reducing conditions. Such structural perturbation modulates electronic microenvironments of Cu, leading to improved d-electron back-donation to the antibonding orbital of *CO intermediates and thus strengthening *CO adsorption. With increased *CO coverage on the defect-rich Cu, we report an acetate selectivity of 56 ± 2% (compared to 31 ± 1% for conventional Cu) and a partial current density of 222 ± 7 mA per square centimeter in CO electroreduction. When run at 400 mA per square centimeter for 40 h in a flow reactor, this catalyst produces 68.3 mmol of acetate throughout. This work highlights the value of a Cu-containing mineral phase in accessing suitable structures for improved selectivity to a single desired C2+ product.

Near-Infrared-Driven Nanorocket for Rapid and Ultrasensitive Detection of MicroRNA.

Herein, by introducing gold nanostars (AuNSs) as fuel core, a near-infrared-driven nanorocket (NIDNR) with pretty fast walking was exploited for ultrasensitive miRNA detection. Compared with traditional nanomaterials-comprised nanomachines (NMs), the NIDNR possesses much better kinetic and thermodynamic performance owing to the extra photothermal driving force from localized surface plasmon (LSP). Impressively, the whole reaction time of NIDNR down to 15 min was realized, which is almost more than 8 times beyond those of conventional DNA-based NMs. This way, the inherent obstacle of traditional NMs, including long reaction time and low efficiency, could be easily addressed. As a proof of concept, the NIDNR was successfully applied to develop an electrochemical biosensing platform for rapid and sensitive detection of miRNA with an LOD down to 2.95 aM and achieved the real-time assay of real biological samples from human hepatocellular carcinoma cells (MHCC97L) and HeLa, thus providing an innovative insight to design more versatile DNA nanomachines for ultimate application in biosensing platform construction and clinical sample detection.

Controllable Three-Dimensional DNA Nanomachine-Mediated Electrochemical Biosensing Platform for Rapid and Ultrasensitive Detection of MicroRNA.

In this work, a high-efficiency controllable three-dimensional (3D) DNA nanomachine (CDNM) was reasonably developed by regulating the diameter of the core and the length of the DNAzyme cantilever, which acquired greater amplification efficiency and speedier walking rate than traditional 3D DNA nanomachines with gold nanoparticles as the cores and DNAzymes as the walking arms. Significantly, once the target miRNA-21 existed, a large number of silent DNAzymes on the CDNM could be activated by enzyme-free-target-recycling amplification (EFTRA) to achieve fast cleavage and walking on the biosensor surface under the interaction of Mg2+. Impressively, when the diameter of the core was 40 nm and the length of the DNAzyme cantilever was 5 nm (15 bp), the CDNM could complete the reaction process in 60 min that was at least twice shorter than those of conventional DNA nanomachines. Moreover, the designed electrochemical biosensor successfully detected target miRNA-21 at an ultrasensitive level with a wide response range (100 aM to 1 nM) and a low detection limit (33.1 aM). Therefore, the developed CDNM provides a new idea for exploring functional DNA nanomachines in the field of biosensing for applications.

Aluminum(III)-Based Organic Nanofibrous Gels as an Aggregation-Induced Electrochemiluminescence Emitter Combined with a Rigid Triplex DNA Walker as a Signal Magnifier for Ultrasensitive DNA Assay.

Due to effective tackling of the problems of aggregation-caused quenching of traditional ECL emitters, aggregation-induced electrochemiluminescence (AIECL) has emerged as a research hotspot in aqueous detection and sensing. However, the existing AIECL emitters still encounter the bottlenecks of low ECL efficiency, poor biocompatibility, and high cost. Herein, aluminum(III)-based organic nanofibrous gels (AOGs) are used as a novel AIECL emitter to construct a rapid and ultrasensitive sensing platform for the detection of Flu A virus biomarker DNA (fDNA) with the assistance of a high-speed and hyper-efficient signal magnifier, a rigid triplex DNA walker (T-DNA walker). The proposed AOGs with three-dimensional (3D) nanofiber morphology are assembled in one step within about 15 s by the ligand 2,2':6',2″-terpyridine-4'-carboxylic acid (TPY-COOH) and cheap metal ion Al3+, which demonstrates an efficient ECL response and outstanding biocompatibility. Impressively, on the basis of loop-mediated isothermal amplification-generated hydrogen ions (LAMP-H+), the target-induced pH-responsive rigid T-DNA walker overcomes the limitations of conventional single or duplex DNA walkers in walking trajectory and efficiency due to the entanglement and lodging of leg DNA, exhibiting high stability, controllability, and walking efficiency. Therefore, AOGs with excellent AIECL performance were combined with a CG-C+ T-DNA nanomachine with high walking efficiency and stability, and the proposed "on-off" ECL biosensor displayed a low detection limit down to 23 ag·µL-1 for target fDNA. Also, the strategy provided a useful platform for rapid and sensitive monitoring of biomolecules, considerably broadening its potential applications in luminescent molecular devices, clinical diagnosis, and sensing analysis.

Ultrasensitive Electrochemiluminescence Biosensor Based on 2D Co3O4 Nanosheets as a Coreaction Accelerator and Highly Ordered Rolling DNA Nanomachine as a Signal Amplifier for the Detection of MicroRNA.

A novel ultrasensitive electrochemiluminescence (ECL) biosensor was constructed using two-dimensional (2D) Co3O4 nanosheets as a novel coreaction accelerator of the luminol/H2O2 ECL system for the detection of microRNA-21 (miRNA-21). Impressively, coreaction accelerator 2D Co3O4 nanosheets with effective mutual conversion of the Co2+/Co3+ redox pair and abundant active sites could promote the decomposition of coreactant H2O2 to generate more superoxide anion radicals (O2•-), which reacted with luminol for significantly enhancing ECL signals. Furthermore, the trace target miRNA-21 was transformed into a large number of G-wires through the strand displacement amplification (SDA) process to self-assemble the highly ordered rolling DNA nanomachine (HORDNM), which could tremendously improve the detection sensitivity of biosensors. Hence, on the basis of the novel luminol/H2O2/2D Co3O4 nanosheet ternary ECL system, the biosensor implemented ultrasensitive detection of miRNA-21 with a detection limit as low as 4.1 aM, which provided a novel strategy to design an effective ECL emitter for ultrasensitive detection of biomarkers for early disease diagnosis.

High-Efficiency 3D DNA Walker Immobilized by a DNA Tetrahedral Nanostructure for Fast and Ultrasensitive Electrochemical Detection of MiRNA.

Herein, by directly limiting the reaction space, an ingenious three-dimensional (3D) DNA walker (IDW) with high walking efficiency is developed for rapid and sensitive detection of miRNA. Compared with the traditional DNA walker, the IDW immobilized by the DNA tetrahedral nanostructure (DTN) brings stronger kinetic and thermodynamic favorability resulting from its improved local concentration and space confinement effect, accompanied by a quite faster reaction speed and much better walking efficiency. Once traces of target miRNA-21 react with the prelocked IDW, the IDW could be largely activated and walk on the interface of the electrode to trigger the cleavage of H2 with the assistance of Mg2+, resulting in the release of amounts of methylene blue (MB) labeled on H2 from the electrode surface and the obvious decrease of the electrode signal. Impressively, the IDW reveals a conversion efficiency as high as 9.33 × 108 in 30 min with a much fast reaction speed, which is at least five times beyond that of typical DNA walkers. Therefore, the IDW could address the inherent challenges of the traditional DNA walker easily: slow walking speed and low efficiency. Notably, the IDW as a DNA nanomachine was utilized to construct a sensitive sensing platform for rapid miRNA-21 detection with a limit of detection (LOD) of 19.8 aM and realize the highly sensitive assay of biomarker miRNA-21 in the total RNA lysates of cancer cell. The strategy thus helps in the design of a versatile nucleic acid conversion and signal amplification approach for practical applications in the areas of biosensing assay, DNA nanotechnology, and clinical diagnosis.

Genetic spectrum and clinical features in a cohort of Chinese patients with isolated dystonia.

Dystonia is a genetically and phenotypically heterogeneous disorder that occurs in isolation (isolated dystonia) or in combination with other movement disorders. To determine the genetic spectrum in isolated dystonia, we enrolled 88 patients with isolated dystonia for whole-exome sequencing (WES). Seventeen mutations, including nine novel ones, were identified in 19 of the 88 patients, providing a 21.59% positive molecular diagnostic rate. Eleven distinct genes were involved, of which TOR1A and THAP1 accounted for 47.37% (9/19) of the positive cases. A novel missense variant, p.S225R in TOR1A, was found in a patient with adolescence-onset generalized dystonia. Cellular experiments revealed that p.S255R results in the abnormal aggregation of Torsin-1A encoding by TOR1A. In addition, we reviewed the clinical and genetic features of the isolated dystonia patients carrying TOR1A, THAP1, ANO3, and GNAL mutations in the Chinese population. Our results expand the genetic spectrum and clinical profiles of patients with isolated dystonia and demonstrate WES as an effective strategy for the molecular diagnosis of isolated dystonia.

Simultaneous Determination of Rifamycin Antibiotics and Their Active Metabolites in Human Plasma Using UHPLC-MS/MS to Evaluate Their Impact on Target Peak Concentrations: A Short Communication.

BACKGROUND: Standard and proper antituberculosis (anti-TB) treatment is essential for patients with TB, and rifamycin antibiotics are key components of anti-TB therapy. Therapeutic drug monitoring (TDM) of rifamycin antibiotics can shorten the time to response and complete treatment of TB. Notably, antimicrobial activities of the major active metabolites of rifamycin are similar to those of their parent compounds. Thus, a rapid and simple assay was developed for simultaneous determination of rifamycin antibiotics and their major active metabolites in plasma to evaluate their impact on target peak concentrations. Here, the authors have developed and validated a method for simultaneous determination of rifamycin antibiotics and their active metabolites in human plasma using ultrahigh-performance liquid chromatography tandem mass spectrometry. METHODS: Analytical validation of the assay was performed in accordance with the bioanalytical method validation guidance for industry described by the US Food and Drug Administration and the guidelines for bioanalytical method validation described by the European Medicines Agency. RESULTS: The drug concentration quantification method for rifamycin antibiotics, including rifampicin, rifabutin, and rifapentine, and their major active metabolites was validated. Significant differences in the proportions of active metabolites in rifamycin antibiotics may affect the redefinition of their effective concentration ranges in the plasma. The method developed herein is expected to redefine the ranges of "true" effective concentrations of rifamycin antibiotics (including parent compounds and their active metabolites). CONCLUSIONS: The validated method can be successfully applied for high-throughput analysis of rifamycin antibiotics and their active metabolites for TDM in patients receiving anti-TB treatment regimens containing these antibiotics. Proportions of active metabolites in rifamycin antibiotics markedly varied among individuals. Depending on the clinical indications of patients, the therapeutic ranges for rifamycin antibiotics may be redefined.

An intramolecular vibrationally excited intermolecular potential energy surface and predicted 2OH overtone spectroscopy of H2O-Kr.

A new five-dimensional potential energy surface (PES) for H2O-Kr which explicitly includes the intramolecular 2OH overtone state of the H2O monomer is presented. The intermolecular potential energies were evaluated using explicitly correlated coupled cluster theory [CCSD(T)-F12] with a large basis set. Four vibrationally averaged analytical intermolecular PESs for H2O-Kr with H2O molecules in its |00+〉, |02+〉, |02-〉, and |11+〉 states are obtained by fitting to the multi-dimensional Morse/Long-Range potential function form. Each vibrationally averaged PES fitted to 578 points has root-mean-square (RMS) deviations smaller than 0.14 cm-1 and requires only 58 parameters. The combined radial discrete variable representation/angular finite basis representation method and the Lanczos algorithm were employed to calculate the rovibrational energy levels for |00+〉, |02+〉, |02-〉, and |11+〉 states of the H2O-Kr complexes. The calculated |02-〉Πf/e(101) ← |00+〉Σe(000) and |02+〉Πf/e(110) ← |00+〉Σe(101) infrared transitions are in excellent agreement with the experimental values with RMS discrepancies being only 0.007 and 0.016 cm-1, respectively. These analytical PESs can be used to provide reliable theoretical guidance for future infrared overtone spectroscopy of H2O-Kr.

Unraveling the Synergistic Effect of Heteroatomic Substitution and Vacancy Engineering in CoFe2O4 for Superior Electrocatalysis Performance.

Metal ion substitution and anion exchange are two effective strategies for regulating the electronic and geometric structure of spinel. However, the optimal location of foreign metallic cations and the exact role of these metals and anions remain elusive. Herein, CoFe2O4-based hollow nanospheres with outstanding oxygen evolution reaction activity are prepared by Cr3+ substitution and S2- exchange. X-ray absorption spectra and theoretical calculations reveal that Cr3+ can be precisely doped into octahedral (Oh) Fe sites and simultaneously induce Co vacancy, which can activate adjacent tetrahedral (Td) Fe3+. Furthermore, S2- exchange results in structure distortion of Td-Fe due to compressive strain effect. The change in the local geometry of Td-Fe causes the *OOH intermediate to deviate from the y-axis plane, thus enhancing the adsorption of the *OOH. The Co vacancy and S2- exchange can adjust the geometric and electronic structure of Td-Fe, thus activating the inert Td-Fe and improving the electrochemical performance.

Design Principles for Maximizing Hole Utilization of Semiconductor Quantum Wires toward Efficient Photocatalysis.

Maximizing hole-transfer kinetics-usually a rate-determining step in semiconductor-based artificial photosynthesis-is pivotal for simultaneously enabling high-efficiency solar hydrogen production and hole utilization. However, this remains elusive yet as efforts are largely focused on optimizing the electron-involved half-reactions only by empirically employing sacrificial electron donors (SEDs) to consume the wasted holes. Using high-quality ZnSe quantum wires as models, we show that how hole-transfer processes in different SEDs affect their photocatalytic performances. We found that larger driving forces of SEDs monotonically enhance hole-transfer rates and photocatalytic performances by almost three orders of magnitude, a result conforming well with the Auger-assisted hole-transfer model in quantum-confined systems. Intriguingly, further loading Pt cocatalyts can yield either an Auger-assisted model or a Marcus inverted region for electron transfer, depending on the competing hole-transfer kinetics in SEDs.

Interfacial Engineering of Ni/V2 O3 Heterostructure Catalyst for Boosting Hydrogen Oxidation Reaction in Alkaline Electrolytes.

Alkaline fuel cells can permit the adoption of platinum group metal-free (PGM-free) catalysts and cheap bipolar plates, thus further lowering the cost. With the exploration of PGM-free hydrogen oxidation reaction (HOR) catalysts, nickel-based compounds have been considered as the most promising HOR catalysts in alkali. Here we report an interfacial engineering through the formation of nickel-vanadium oxide (Ni/V2 O3 ) heterostructures to activate Ni for efficient HOR catalysis in alkali. The strong electron transfer from Ni to V2 O3 could modulate the electronic structure of Ni sites. The optimal Ni/V2 O3 catalyst exhibits a high intrinsic activity of 0.038 mA cm-2 and outstanding stability. Experimental and theoretical studies reveal that Ni/V2 O3 interface as the active sites can enable to optimize the hydrogen and hydroxyl bindings, as well as protect metallic Ni from extensive oxidation, thus achieving the notable activity and durability.