High-Performance Electrochemical and Photoelectrochemical Water Splitting at Neutral pH by Ir Nanocluster-Anchored CoFe-Layered Double Hydroxide Nanosheets.

Highly efficient electrocatalysts for the oxygen evolution reaction (OER) in neutral electrolytes are indispensable for practical electrochemical and photoelectrochemical water splitting technologies. However, there is a lack of good, neutral OER electrocatalysts because of the poor stability when H+ accumulates during the OER and slow OER kinetics at neutral pH. Herein, we report Ir species nanocluster-anchored, Co/Fe-layered double hydroxide (LDH) nanostructures in which the crystalline nature of LDH-restrained corrosion associated with H+ and the Ir species dramatically enhanced the OEC kinetics at neutral pH. The optimized OER electrocatalyst demonstrated a low overpotential of 323 mV (at 10 mA cm-2) and a record low Tafel slope of 42.8 mV dec-1. When it was integrated with an organic semiconductor-based photoanode, we obtained a photocurrent density of 15.2 mA cm-2 at 1.23 V versus reversible hydrogen in neutral electrolyte, which is the highest among all reported photoanodes to our knowledge.

Phosphorus-Modified Palladium and Tungsten Carbide/Mesoporous Carbon Composite for Hydrogen Oxidation Reaction of Proton Exchange Membrane Fuel Cells.

A composite material of tungsten carbide and mesoporous carbon was synthesized by the sol-gel polycondensation of resorcinol and formaldehyde, using cetyltrimethylammonium bromide as a surfactant and Ludox HS-40 as a porogen, and served as a support for Pd-based electrodes. Phosphorus-modified Pd particles were deposited onto the support using an NH3-mediated polyol reduction method facilitated by sodium hypophosphite. Remarkably small Pd nanoparticles with a diameter of ca. 4 nm were formed by the phosphorus modification. Owing to the high dispersion of Pd and its strong interaction with tungsten carbide, the Pd nanoparticles embedded in the tungsten carbide/mesoporous carbon composite exhibited a hydrogen oxidation activity approximately twice as high as that of the commercial Pt/C catalyst under the anode reaction conditions of proton exchange membrane fuel cells.

CO2 Enrichment Boosts Highly Selective Infrared-Light-Driven CO2 Conversion to CH4 by UiO-66/Co9S8 Photocatalyst.

Photocatalytic CO2 reduction to high-value chemicals is an attractive approach to mitigate climate change, but it remains a great challenge to produce a specific product selectively by IR light. Hence, UiO-66/Co9S8 composite is designed to couple the advantages of metallic photocatalysts and porous CO2 adsorbers for IR-light-driven CO2-to-CH4 conversion. The metallic nature of Co9S8 endows UiO-66/Co9S8 with exceptional IR light absorption, while UiO-66 dramatically enhances its local CO2 concentration, revealed by finite-element method simulations. As a result, Co9S8 or UiO-66 alone does not show observable IR-light photocatalytic activity, whereas UiO-66/Co9S8 exhibits exceptional activity. The CH4 evolution rate over UiO-66/Co9S8 reaches 25.7 µmol g-1 h-1 with ca.100% selectivity under IR light irradiation, outperforming most reported catalysts under similar reaction conditions. The X-ray absorption fine structure spectroscopy spectra verify the presence of two distinct Co sites and confirm the existence of metallic Co─Co bond in Co9S8. Energy diagrams analysis and transient absorption spectra manifest that CO2 reduction mainly occurs on Co9S8 for UiO-66/Co9S8, while density functional theory calculations demonstrate that high-electron-density Co1 sites are the key active sites, possessing lower energy barriers for further protonation of *CO, leading to the ultra-high selectivity toward CH4.

An in situ fluorine and ex situ titanium two-step co-doping strategy for efficient solar water splitting by hematite photoanodes.

A unique two-step co-doping strategy of in situ fluorine doping followed by ex situ titanium doping enhances the performance of the hematite photoanode in photoelectrochemical water splitting much more effectively than single-step co-doping strategies that are either all in situ or all ex situ. The optimized fluorine, titanium co-doped Fe2O3 photoanode without any cocatalyst achieves 1.61 mA cm-2 at 1.23 VRHE under 100 mW cm-2 solar irradiation, which is ∼2 and 3 times those of titanium or fluorine singly-doped Fe2O3 photoanodes, respectively. The promotional effect is attributed to the synergy of the two dopants, in which the doped fluorine anion substitutes oxygen of Fe2O3 to increase the positive charges of iron sites, while the doped titanium cation substitutes iron to increase free electrons. Moreover, excess titanium on the surface suppresses the drain of in situ doped fluorine and agglomeration of hematite during the high-temperature annealing process, and passivates the surface trap states to further promote the synergy effects of the two dopants.

Gradient tantalum-doped hematite homojunction photoanode improves both photocurrents and turn-on voltage for solar water splitting.

Hematite has a great potential as a photoanode for photoelectrochemical (PEC) water splitting by converting solar energy into hydrogen fuels, but the solar-to-hydrogen conversion efficiency of state-of-the-art hematite photoelectrodes are still far below the values required for practical hydrogen production. Here, we report a core-shell formation of gradient tantalum-doped hematite homojunction nanorods by combination of hydrothermal regrowth strategy and hybrid microwave annealing, which enhances the photocurrent density and reduces the turn-on voltage simultaneously. The unusual bi-functional effects originate from the passivation of the surface states and intrinsic built-in electric field by the homojunction formation. The additional driving force provided by the field can effectively suppress charge-carrier recombination both in the bulk and on the surface of hematite, especially at lower potentials. Moreover, the synthesized homojunction shows a remarkable synergy with NiFe(OH)x cocatalyst with significant additional improvements of photocurrent density and cathodic shift of turn-on voltage. The work has nicely demonstrated multiple collaborative strategies of gradient doping, homojunction formation, and cocatalyst modification, and the concept could shed light on designing and constructing the efficient nanostructures of semiconductor photoelectrodes in the field of solar energy conversion.

Activating the surface and bulk of hematite photoanodes to improve solar water splitting.

A simple electrochemical activation treatment is proposed to improve effectively the photoelectrochemical performance of Nb,Sn co-doped hematite nanorods. The activation process involves an initial thrice cathodic scanning (reduction) and a subsequent thrice anodic scanning (oxidation), which modifies both the surface and bulk properties of the Nb,Sn:Fe2O3 photoanode. First, it selectively removes the surface components to different extents endowing the hematite surface with fewer defects and richer Nb-O and Sn-O bonds and thus passivates the surface trap states. The surface passivation effect also enhances the photoelectrochemical stability of the photoanode. Finally, more Fe2+ ions or oxygen vacancies are generated in the bulk of hematite to enhance its conductivity. As a result, the photocurrent density is increased by 62.3% from 1.88 to 3.05 mA cm-2 at 1.23 VRHE, the photocurrent onset potential shifts cathodically by ∼70 mV, and photoelectrochemical stability improves remarkably relative to the pristine photoanode under simulated sunlight (100 mW cm-2).

Characterization of monolithic matrix patch system containing tulobuterol.

The aim of this study was to investigate the effect of the functional groups in acrylic adhesive on tulobuterol uptake, release rate and permeation rate across rat dorsal skin. In addition, the relationship between these parameters was identified in order to formulate the monolithic matrix patch system. Seven acrylate pressure sensitive adhesives were used in this study with three different functional groups as follows: (1) no functionality (DT-4098), (2) hydroxyl group (DT-2287, DT-2510, DT-2525, DT-2516), and (3) carboxyl group (DT-2353, DT-2852). Tulobuterol-uptake in PSA was determined by the drug-uptake method. The amount of tulobuterol-uptake in acrylic polymers with a carboxyl group was higher than those in acrylate pressure sensitive adhesives with either a hydroxyl group or a nonfunctional group. The release rate of tulobuterol from the monolithic patches was evaluated and DT-2353 and DT-2852, which contained a carboxyl group, showed lower release rates of tulobuterol than the other acrylate pressure sensitive adhesives. The skin permeation of tulobuterol was investigated using excised rat dorsal skin and the permeation rate of tulobuterol from DT-2353 and DT-2852 was also lower than the other acrylate pressure sensitive adhesives. Taking into consideration the relationship between all the parameters, pressure sensitive adhesives can be categorized into two groups: those containing a carboxylic acid functional group and those containing a non-carboxylic group. These results indicate that there was an interaction between the secondary amino group of tulobuterol and the carboxyl group of the acrylate polymer. Therefore, we suggest that a drug's chemical structure and functional groups in pressure sensitive adhesives must be considered in order to formulate a transdermal patch system.

Orbital Angular Momentum (OAM) Antennas via Mode Combining and Canceling in Near-field.

Orbital angular momentum (OAM) mode combining and canceling in the near-field was investigated using a Cassegrain dual-reflectarray antenna composed of multiple microstrip patches on the main and sub-reflectarrays. Microstrip patches on dielectric substrates were designed to radiate the particular OAM modes for arithmetic mode combining, where two OAM wave-generating reflectarrays are very closely placed in the near-field. We conducted near-field antenna measurements at 18 [GHz] by manually replacing the sub-reflectarray substrates with different OAM mode numbers of 0, ±1, when the OAM mode number of the main reflectarray was fixed to +1. We subsequently checked the azimuthal phase distributions of the reflected total electromagnetic waves in the near-field, and verified that the OAM waves mutually reflected from the main and sub-reflectarrays are added or subtracted to each other according to their OAM mode numbers. Based on our proposal, an OAM mode-canceling reflectarray antenna was designed, and the following measurements indicate that the antenna has a better reflection bandwidth and antenna gain than a conventional reflectarray antenna. The concept of OAM mode canceling in the near-field can contribute widely to a new type of low-profile, broad-reflection bandwidth, and high-gain antenna.

Multiplexed Cassegrain Reflector Antenna for Simultaneous Generation of Three Orbital Angular Momentum (OAM) Modes.

A multiplexed Cassegrain reflector antenna with a 2 × 2 open-ended rectangular waveguide (OERW) matrix feed and an orbital angular momentum (OAM) mode mux is proposed for the simultaneous generation of three OAM modes (l = 0, ±1). The OAM mode mux (OMM) was designed using sequential combinations of quadrature hybrids, crossovers, and phase shifters to multiplex and demultiplex three OAM modes at the same time. The 2 × 2 OERW matrix feed and the OMM were separately measured and their performances were verified according to proposed theories. A near-field antenna measurement for a multiplexed Cassegrain reflector antenna was conducted to obtain the far-field magnitude and phase patterns around polar elevation angle θ and azimuthal angle ϕ, thus confirming that our antenna can produce three OAM modes simultaneously. We also measured the communication link characteristics of two identical multiplexed antennas. The measurement results show that the channel isolation of three OAM modes is more than 12.7 [dB] and 17 [dB] for fixed and compensated receiver positions, respectively, indicating that the proposed antenna system can be used for independent communication links with the same frequency and polarisation.

Indications for supramalleolar osteotomy in patients with ankle osteoarthritis and varus deformity.

BACKGROUND: Osteotomies are reported to be effective for the treatment of most cases of primary and traumatic moderate osteoarthritis of the ankle joint. Because of unsatisfactory results following supramalleolar tibial osteotomy in several of our patients, we investigated the cause of the unsatisfactory results and the indications for this surgical procedure. METHODS: Supramalleolar tibial osteotomy combined with fibular osteotomy was performed in sixteen ankles (sixteen patients) to treat moderate medial ankle osteoarthritis. The median duration of follow-up was 2.3 years (range, one to 6.5 years). Clinical assessment was performed with use of the American Orthopaedic Foot & Ankle Society (AOFAS) scale, and the osteoarthritis stage was determined radiographically with use of the modified Takakura classification system. Clinical and radiographic results were compared among groups defined by high (≥9.5°) or low (≤4°) postoperative talar tilt and by the presence or absence of postoperative lateral subfibular pain. The optimal threshold of preoperative talar tilt for predicting high postoperative talar tilt was determined with use of receiver operating characteristic curve analysis. RESULTS: The mean AOFAS score, mean Takakura stage, and mean values of all radiographic parameters were improved significantly after surgery. The preoperative talar tilt was correlated with the postoperative talar tilt (Spearman rho = 0.75, p < 0.01). The mean AOFAS score was higher (p = 0.02) and the mean radiographic stage was lower (p = 0.03) in the group with low postoperative talar tilt than in the group with high talar tilt. The optimal threshold for predicting high postoperative talar tilt was 7.3° of preoperative talar tilt, with a sensitivity of 100% and a specificity of 91.7%. The patients with lateral subfibular pain had a lower mean AOFAS score, a greater angle between the tibia and the ankle surface postoperatively, and greater postoperative heel valgus than those without lateral subfibular pain. CONCLUSIONS: Supramalleolar osteotomy is indicated for the treatment of ankle osteoarthritis in patients with minimal talar tilt and neutral or varus heel alignment.

Supramalleolar Osteotomy in Patients with Varus Ankle Osteoarthritis.

INTRODUCTION: Supramalleolar osteotomies have been reported to be effective in the treatment of moderate primary and traumatic osteoarthritis of the ankle joint. STEP 1 ARTHROSCOPIC EXAMINATION: Perform an arthroscopic examination prior to the osteotomy in every patient to evaluate the status of the articular cartilage of the tibia and talus. STEP 2 FIBULAR OSTEOTOMY: Bend a seven-hole plate slightly more than the natural contour of the distal part of the fibula, insert screws, and complete the osteotomy. STEP 3 TIBIAL OSTEOTOMY: Attempt to achieve a tibial-talar angle of 95° (5° of valgus). STEP 4 FIXATION AND BONE-GRAFTING OF TIBIAL OSTEOTOMY SITE: Apply a seven-hole plate and pack graft into the osteotomy gap. STEP 5 POSTOPERATIVE CARE: After routine wound closure, apply a short leg cast and do not allow weight-bearing for six weeks after surgery. RESULTS: In our series of sixteen patients with moderate medial ankle osteoarthritis, the mean American Orthopaedic Foot & Ankle Society (AOFAS) score, radiographic stage, and values for all radiographic parameters measured improved significantly after surgery. WHAT TO WATCH FOR: IndicationsContraindicationsPitfalls & Challenges.