Nanoconfinement Enables Photoelectrochemical Selective Oxidation of Glycerol via the Microscale Fluid Effect.

The glycerol oxidation reaction (GOR) run with photoelectrochemical cells (PECs) is one of the most promising ways to upgrade biomass because it is thermodynamically favorable, while irreversible overoxidation leads to unsatisfactory product selectivities. Herein, a tunable one-dimensional nanoconfined environment was introduced into the GOR process, which accelerated mass transfer of glycerol via the microscale fluid effect and changed the main oxidation product from formic acid (FA) to glyceraldehyde (GLD), which led to retention of the heavier multicarbon products. The rate of glycerol diffusion in the nanochannels increased by a factor of 4.92 with decreasing inner diameters. The main product from the PEC-selective oxidation of glycerol changed from the C1 product FA to the C3 product GLD with a great selectivity of 60.7%. This work provides a favorable approach for inhibiting further oxidation of multicarbon products and illustrates the importance of microenvironmental regulation in biomass oxidation.

Functional Sulfate Additive-Derived Interfacial Layer for Enhanced Electrochemical Stability of PEO-Based Polymer Electrolytes.

Solid-state electrolyte batteries have attracted significant interest as promising next-generation batteries due to their achievable high energy densities and nonflammability. In particular, curable polymer network gel electrolytes exhibit superior ion conductivity and interfacial adhesion with electrodes compared to oxide or sulfide solid electrolytes, bringing them closer to commercialization. However, the limited electrochemical stability of matrix polymers, particularly those based on poly (ethylene oxide) (PEO), presents challenges in achieving stable electrochemical performance in high-voltage lithium metal batteries. Here, these studies report a sulfate additive-incorporated thermally crosslinked gel-type polymer electrolyte (SA-TGPE) composed of a PEO-based polymer matrix and a functional sulfate additive, 1,3-propanediolcyclic sulfate (PCS), which forms stable interfacial layers on electrodes. The electrode-electrolyte interface modified by the PCS enhances the electrochemical stability of the polymer electrolyte, effectively alleviating decomposition of the PEO-based polymer matrix on the cathode. Moreover, it also mitigates side reactions of the Ni-rich NCM cathode and dendrites of lithium metal anode. These studies provide a novel perspective by utilizing interfacial modification through electrolyte additives to resolve the electrochemical instability of PEO-based polymer electrolytes in high-voltage lithium metal batteries.

Interlayer Engineering and Prelithiation: Empowering Si Anodes for Low-Pressure-Operating All-Solid-State Batteries.

Silicon (Si) anodes, free from the dendritic growth concerns found in lithium (Li) metal anodes, offer a promising alternative for high-energy all-solid-state batteries (ASSBs). However, most advancements in Si anodes have been achieved under impractical high operating pressures, which can mask detrimental electrochemo-mechanical issues. Herein, we effectively address the challenges related to the low-pressure operation of Si anodes in ASSBs by introducing an silver (Ag) interlayer between the solid electrolyte layer (Li6PS5Cl) and anode and prelithiating the anodes. The Si composite electrodes, consisting of Si/polyvinylidene fluoride/carbon nanotubes, are optimized for suitable mechanical properties and electrical connectivity. Although the impact of the Ag interlayer is insignificant at an exceedingly high operating pressure of 70 MPa, it substantially enhances the interfacial contacts under a practical low operating pressure of 15 MPa. Thus, Ag-coated Si anodes outperform bare Si anodes (discharge capacity: 2430 vs 1560 mA h g-1). The robust interfacial contact is attributed to the deformable, adhesive properties and protective role of the in situ lithiated Ag interlayer, as evidenced by comprehensive ex situ analyses. Operando electrochemical pressiometry is used effectively to probe the strong interface for Ag-coated Si anodes. Furthermore, prelithiation through the thermal evaporation deposition of Li metal significantly improves the cycling performance.

Heterogeneous Catalyst as a Functional Substrate Governing the Shape of Electrochemical Precipitates in Oxygen-Fueled Rechargeable Batteries.

Lithium-oxygen batteries have the potential to become the most eminent solution for future energy storage with their theoretical energy density exceeding all existing batteries. However, the insulating and insoluble discharge product (lithium peroxide; Li2O2) impairs practical application. Conventional catalyst designs based on the electronic structure and interfacial charge transfer descriptors have not been able to overcome these limitations due to Li2O2. Herein, we revisit the role of heterogeneous catalysts as substrates to regulate Li2O2 growth and the formation of solid/solid reaction interfaces. We demonstrate that controlled solid/solid interfacial structure design is a critical performance parameter beyond the inherent electronic structure. In particular, the Cu2O substrate in this study induces a homogeneous deposition of Pd atoms, which leads to well-controlled growth of Li2O2 resolving mass and charge transport limits (i.e., the bottleneck of oxygen reduction/evolution reactions), thus improving reversibility, capacity, and durability of the cells by dissipating electrochemical and mechanical stress. We thus verified the essential role of solid/solid interfaces to regulate the nucleation and growth process of Li2O2 in lithium-oxygen batteries.

Tailoring the Nanoporosity and Photoactivity of Metal-Organic Frameworks With Rigid Dye Modulators for Toluene Purification.

Facile synthesis of hierarchically porous metal-organic frameworks (MOFs) with adjustable porosity and high crystallinity attracts great attention yet remains challenging. Herein, a micromolar amount of dye-based modulator (Rhodamine B (RhB)) is employed to easily and controllably tailor the pore size of a Ti-based metal-organic framework (MIL-125-NH2 ). The RhB used in this method is easily removed by washing or photodegradation, avoiding secondary posttreatment. It is demonstrated that the carboxyl functional group and the steric effects of RhB are indispensable for enlarging the pore size of the MIL-125-NH2 . The resulting hierarchically porous MIL-125-NH2 (RH-MIL-125-NH2 ) exhibits optimized adsorption and photocatalytic activity because the newly formed mesopore with defects concurrently facilitates mass transport of guest molecules (toluene) and photogenerated charge separation. This work offers a meaningful basis for the construction of hierarchically porous MOFs and demonstrates the superiority of the hierarchical pore structure for adsorption and heterogeneous catalysis.

Platelet-derived mitochondria transfer facilitates wound-closure by modulating ROS levels in dermal fibroblasts.

Platelets are known to improve the wound-repair capacity of mesenchymal stem cells (MSCs) by transferring mitochondria intercellularly. This study aimed to investigate whether direct transfer of mitochondria (pl-MT) isolated from platelets could enhance wound healing in vitro using a cell-based model. Wound repairs were assessed by 2D gap closure experiment in wound scratch assay using human dermal fibroblasts (hDFs). Results demonstrated that pl-MT were successfully internalized into hDFs. It increased cell proliferation and promoted the closure of wound gap. Importantly, pl-MT suppressed both intracellular and mitochondrial ROS production induced by hydrogen peroxide, cisplatin, and TGF-ß in hDFs. Taken together, these results suggest that pl-MT transfer might be used as a potential therapeutic strategy for wound repair.

What is the context? During the wound healing process, abnormal regulation of ROS and inflammation delays the healing process, resulting in chronic non-healing wounds.Mitochondria are key organelles responsible for the ROS generation. Mitochondrial dysfunction has been implicated in delayed wound repair.Mitochondria transfer, which utilizes intact mitochondria isolated from healthy cells to recover from disease, has been applied in various clinical studies, but additional evidence is needed to apply it to wound healing.What is new? In this study, we chose platelets as a cell source for mitochondrial transfer. We isolated the functional mitochondria from platelets and applied them to wound healing.What is the impact? This study provides evidence that platelet-derived mitochondria (pl-MT) improve the wound healing progress by increasing the viability of dermal fibroblasts and suppressing intracellular and mitochondrial ROS production.Platelets have also been demonstrated to be a suitable cell source for mitochondrial transfer.

Disordered-Layer-Mediated Reverse Metal-Oxide Interactions for Enhanced Photocatalytic Water Splitting.

In heterogeneous catalysts, metal-oxide interactions occur spontaneously but often in an undesired way leading to the oxidation of metal nanoparticles. Manipulating such interactions to produce highly active surface of metal nanoparticles can warrant the optimal catalytic activity but has not been established to date. Here we report that a prior reduced TiO2 support can reverse the interaction with Pt nanoparticles and augment the metallic state of Pt, exhibiting a 3-fold increase in hydrogen production rate compared to that of conventional Pt/TiO2. Spatially resolved electron energy loss spectroscopy of the Ti valence state and the electron density distribution within Pt nanoparticles provide direct evidence supporting that the Pt/TiO2/H2O triple junctions are the most active catalytic sites for water reduction. Our reverse metal-oxide interaction scheme provides a breakthrough in the stagnated hydrogen production efficiency and can be applied to other heterogeneous catalyst systems composed of metal nanoparticles with reducible oxide supports.

Preferred Migration of Mitochondria toward Cells and Tissues with Mitochondrial Damage.

Mitochondria are organelles that play a vital role in cellular survival by supplying ATP and metabolic substrates via oxidative phosphorylation and the Krebs cycle. Hence, mitochondrial dysfunction contributes to many human diseases, including metabolic syndromes, neurodegenerative diseases, cancer, and aging. Mitochondrial transfer between cells has been shown to occur naturally, and mitochondrial transplantation is beneficial for treating mitochondrial dysfunction. In this study, the migration of mitochondria was tracked in vitro and in vivo using mitochondria conjugated with green fluorescent protein (MTGFP). When MTGFP were used in a coculture model, they were selectively internalized into lung fibroblasts, and this selectivity depended on the mitochondrial functional states of the receiving fibroblasts. Compared with MTGFP injected intravenously into normal mice, MTGFP injected into bleomycin-induced idiopathic pulmonary fibrosis model mice localized more abundantly in the lung tissue, indicating that mitochondrial homing to injured tissue occurred. This study shows for the first time that exogenous mitochondria are preferentially trafficked to cells and tissues in which mitochondria are damaged, which has implications for the delivery of therapeutic agents to injured or diseased sites.

Preparation of multilayer periodic nanopatterned WO3-based photoanode by reverse nanoimprinting for water splitting.

Photoelectrochemical (PEC) water splitting has been studied extensively as an environmentally friendly technology for hydrogen production using solar energy. WO3is considered a promising semiconducting material for photoanodes due to its high electron mobility, good hole diffusion length, and chemical stability. Periodic nanostructures of WO3have been investigated for enhancing the PEC performance of WO3-based photoanodes. In this study, facile fabrication of periodic nanostructures of WO3was achieved using reverse nanoimprint lithography, and the multilayer stacking of nanopatterned WO3film was also confirmed. The multilayer nanopatterned WO3films were used as photoanodes for PEC water splitting. The performance of the fabricated photoanode in PEC was 2 times higher than that of planar WO3film due to its higher light absorbance and lower charge transfer resistance.

Influence of dynamic neck motion on the clinical usefulness of multi-positional MRI in cervical degenerative spondylosis.

PURPOSE: The purpose of this study was to find out additional indications for multi-positional MRI in cervical degenerative spondylosis (CDS) patients. MATERIAL AND METHODS: A total of 63 patients with cervical spondylotic myelopathy that underwent multi-positional MRI and X-ray were included. Muhle's grade, C2-7 angle, and C7 slope were measured. Patients were assigned to the stenosis group (Group S) when Muhle's grades were increased by more than two or maximum grade was reached. Other patients were assigned to the maintenance group (Group M). Receiver operating characteristic (ROC) analysis was performed. Statistical significance was accepted for p values of < 0.05. RESULTS: A total of 24 patients were assigned to the S group and 39 patients to the M group. Mean C2-7 angle difference in extension (eC27A) between S and M groups was 10.97° (p = 0.002). The mean inter-group difference between C2-7 angle in extension and neutral positions (e-nC27A) was 14.39° (p = 0.000). Mean C7 slope difference in neutral position was - 6.53° (p = 0.002). Based on areas under ROC curves (AUCs), e-nC27A, eC27A, and negative C7 slope had AUCs of 0.934 (95% CI 0.876-0.992), 0.752 (95% CI 0.624-0.880), and 0.720 (95% CI 0.588-0.851), respectively. The optimal cutoff value of e-nC27A was 15.4 degrees, which had a diagnostic accuracy of 88.9%. CONCLUSION: Multi-positional MRI helps to find dynamic cord compressive lesion in CDS patients. The higher eC27A, e-nC27A values and smaller C7 slope were found to increase the likelihood of cervical dynamic stenosis. Among other factors, we recommend multi-positional MRI before surgery especially when a patient's e-nC27A is > 15.4 degrees. LEVEL OF EVIDENCE I: Diagnostic: individual cross-sectional studies with the consistently applied reference standard and blinding.

A new nomenclature system for the surgical treatment of cervical spine deformity, developing, and validation of SOF system.

PURPOSE: To develop and assess the reliability of new nomenclature system that systematically organizes osteotomy techniques and briefly describes the surgical approach, the surgical sequence, and the fixation technique for cervical spine deformity (CSD). METHODS: We developed a new classification system (SOF system) for CSD surgery that describes the sequence of surgical approach (S), the grade of osteotomy (O), and the information of fixation (F) using alphanumeric codes. Twenty CSD osteotomies (8 anterior osteotomies, 12 posterior osteotomies) were included in this study to evaluate the inter- and intra-observer agreement based on operation records. Six observers performed independent evaluations of the operation records in random order. Each observer described 20 CSD surgeries using the SOF system twice (> 30 days between assessments) based on operation records to validate SOF system. RESULTS: Overall agreement (among all six observers at the initial assessment) on the anterior and posterior osteotomy was ICC = 0.96 and ICC = 0.91, respectively. Overall agreement (repeat observations after at least 30 days) on the anterior and posterior osteotomy was ICC = 0.96 and ICC = 0.91, respectively. This data showed that both inter- and intra-observer agreement revealed 'excellent'. CONCLUSION: This study introduces the SOF system of the CSD surgery to understand the surgical sequence, the type of osteotomy and the fixation techniques. The investigation of the inter- and intra-observer agreement revealed 'excellent agreement' for both anterior and posterior osteotomies. Thus, SOF system can provide a consistent description of the various CSD surgeries and its use will provide a common frame for CSD surgery and help communicate between surgeons.

Intraoperative surveillance of the vertebral artery using indocyanine green angiography and Doppler sonography in craniovertebral junction surgeries.

OBJECTIVE: The authors sought to evaluate the usefulness of indocyanine green (ICG) angiography and Doppler sonography for monitoring the vertebral artery (VA) during craniovertebral junction (CVJ) surgery and compare the incidence of VA injury (VAI) between the groups with and without the monitoring of VA using ICG angiography and Doppler sonography. METHODS: In total, 344 consecutive patients enrolled who underwent CVJ surgery. Surgery was performed without intraoperative VA monitoring tools in 262 cases (control group) and with VA monitoring tools in 82 cases (monitoring group). The authors compared the incidence of VAI between groups. The procedure times of ICG angiography, change of VA flow velocity measured by Doppler sonography, and complication were investigated. RESULTS: There were 4 VAI cases in the control group, and the incidence of VAI was 1.5%. Meanwhile, there were no VAI cases in the monitoring group. The procedure time of ICG angiography was less than 5 minutes (mean [± SD] 4.6 ± 2.1 minutes) and VA flow velocity was 11.2 ± 4.5 cm/sec. There were several cases in which the surgical method had to be changed depending on the VA monitoring. The combined use of ICG angiography and Doppler sonography was useful not only to monitor VA patency but also to assess the quality of blood flow during CVJ surgery, especially in the high-risk group of patients. CONCLUSIONS: The combined use of ICG angiography and Doppler sonography enables real-time intraoperative monitoring of the VA by detecting blood flow and flow velocity. As the arteries get closer, they provide auditory and visual feedback to the surgeon. This real-time image guidance could be a useful tool, especially for high-risk patients and inexperienced surgeons, to avoid iatrogenic VAI during any CVJ surgery.

Near-Complete Suppression of Oxygen Evolution for Photoelectrochemical H2O Oxidative H2O2 Synthesis.

Solar energy-assisted water oxidative hydrogen peroxide (H2O2) production on an anode combined with H2 production on a cathode increases the value of solar water splitting, but the challenge of the dominant oxidative product, O2, needs to be overcome. Here, we report a SnO2-x overlayer coated BiVO4 photoanode, which demonstrates the great ability to near-completely suppress O2 evolution for photoelectrochemical (PEC) H2O oxidative H2O2 evolution. Based on the surface hole accumulation measured by surface photovoltage, downward quasi-hole Fermi energy at the photoanode/electrolyte interface and thermodynamic Gibbs free energy between 2-electron and 4-electron competitive reactions, we are able to consider the photoinduced holes of BiVO4 that migrate to the SnO2-x overlayer kinetically favor H2O2 evolution with great selectivity by reduced band bending. The formation of H2O2 may be mediated by the formation of hydroxyl radicals (OH·), from 1-electron water oxidation reactions, as evidenced by spin-trapping electron paramagnetic resonance (EPR) studies conducted herein. In addition to the H2O oxidative H2O2 evolution from PEC water splitting, the SnO2-x/BiVO4 photoanode can also inhibit H2O2 decomposition into O2 under either electrocatalysis or photocatalysis conditions for continuous H2O2 accumulation. Overall, the SnO2-x/BiVO4 photoanode achieves a Faraday efficiency (FE) of over 86% for H2O2 generation in a wide potential region (0.6-2.1 V vs reversible hydrogen electrode (RHE)) and an H2O2 evolution rate averaging 0.825 µmol/min/cm2 at 1.23 V vs RHE under AM 1.5 illumination, corresponding to a solar to H2O2 efficiency of ∼5.6%; this performance surpasses almost all previous solar energy-assisted H2O2 evolution performances. Because of the simultaneous production of H2O2 and H2 by solar water splitting in the PEC cells, our results highlight a potentially greener and more cost-effective approach for "solar-to-fuel" conversion.

Edge functionalized graphene nanoribbons with tunable band edges for carrier transport interlayers in organic-inorganic perovskite solar cells.

Organic based graphene nanoribbons (GNRs) can be good candidates as carrier extraction interlayers for organic/inorganic hybrid perovskite solar cells, owing to the possibility of tuning the band edge energy levels through varying the width and the type of edge functionalization. By using the density functional theory (DFT) method, the electronic structures of H or F edge functionalized armchair type GNRs on MAPbI3(001) are calculated. It is shown that the electronic structure of H- or F-passivated GNRs is almost undisrupted by the non-covalent interaction with the PbI2 surface layer of MAPbI3(001), thereby one can tune the width and edge chemistry of GNRs to enhance the carrier extraction or blocking. Especially all H-GNRs five to ten carbon atoms wide exhibit good matching for hole extraction, while F-GNRs require a specific width for electron extraction. Exploiting the unzipping synthesis of carbon nanotubes in the solution phase, our result provides a facile strategy for efficient carrier extraction.

Effect of cysteine-free human fibroblast growth factor-5s mutant (FGF5sC93S) on hair growth.

Treatment for hair loss is largely limited, and any beneficial effects are often transient. Based on the critical role of the FGF5 isoform, FGF5s, in the hair growth cycle, it may be a good therapeutic candidate for the prevention of hair loss, as well as the promotion of hair growth. To investigate its potential use for hair growth, a mutant form of the FGF5s protein (FGF5sC93S) was generated, expressed, and purified. The FGF5sC93S mutant was able to antagonize FGF5-induced mitogenic activity, which normally triggers the conversion of hair follicles from the anagen phase to the catagen phase. In addition, the FGF5sC93S mutant efficiently suppressed gene expression induced by FGF5 both human outer root sheath (hORS) and human dermal papilla (hDP) cells. Administration of FGF5sC93S proteins onto the scalps of human subjects significantly increased the total number of hairs at 24 weeks. Together, our data demonstrate that a mutant form of the FGF5s protein could be used as a potential hair promoting agent.

Analysis of postoperative dysphagia after anterior cervical decompression and fusion.

Purpose: To investigate the incidence and risk factors of postoperative dysphagia after anterior cervical decompression and fusion (ACDF) in terms of demographic, procedural and anaesthetic perspectives.Materials and methods: Medical records and radiologic data of patients who underwent anterior cervical surgery performed by two surgeons in a single centre between January 2012 and December 2015 were retrospectively analysed. Patients with spinal tumours, infective spondylitis and traumatic cervical pathologies were excluded. Patients with preoperative dysphagia and previous history of anterior cervical surgery were also excluded. Finally, 127 patients were enrolled. Bazaz dysphagia score was used for the diagnosis of postoperative dysphagia.Results: The incidence of postoperative dysphagia was 10.2% at six weeks after ACDF. Nine patients showed mild dysphagia that fully recovered at three months after ACDF. Four patients showed moderate dysphagia that also recovered fully at six months after surgery. The incidence of postoperative dysphagia increased significantly in cases of C4 or C5 level involvements. Age, sex, hypertension, body mass index, postoperative soft tissue swelling, intubation difficulty and intubation tools were not significant risk factors of ACDF. Diabetes mellitus, two surgical levels, the use of plate, long anaesthetic and operative time and large intubation tube size were causative factors of postoperative dysphagia in multivariable analysis (p < 0.05).Conclusions: The incidence of postoperative dysphagia after ACDF was relatively low, and the prognosis was good.

Grain Boundary Healing of Organic-Inorganic Halide Perovskites for Moisture Stability.

Although organic-inorganic halide perovskite (OIHP)-based photovoltaics have high photoconversion efficiency (PCE), their poor humidity stability prevents commercialization. To overcome this critical hurdle, focusing on the grain boundary (GB) of OIHPs, which is the main humidity penetration channel, is crucial. Herein, pressure-induced crystallization of OIHP films prepared with controlled mold geometries is demonstrated as a GB-healing technique to obtain high moisture stability. When exposed to 85% RH at 30 °C, OIHP films fabricated by pressure-induced crystallization have enhanced moisture stability due to the enlarged OIHP grain size and low-angle GBs. The crystallographic and optical properties indicate the effect of applying pressure onto OIHP films in terms of moisture stability. The photovoltaic devices with pressure-induced crystallization exhibited dramatically stabilized performance and sustained over 0.95 normalized PCE after 200 h at 40% RH and 30 °C.

Dopamine receptor antagonists induce differentiation of PC-3 human prostate cancer cell-derived cancer stem cell-like cells.

BACKGROUND: The objective of this study was to determine whether PC-3 human prostate cancer cell-derived cancer stem cells (CSC)-like cells grown in a regular cell culture plate not coated with a matrix molecule might be useful for finding differentiation-inducing agents that could alter properties of prostate CSC. METHODS: Monolayer cells prepared from sphere culture of PC-3 cells were characterized for the presence of pluripotency and tumorigenicity. They were then applied to screen a compound library to find compounds that could induce morphology changes of cells. Mechanisms of action of compounds selected from the chemical library that induced the loss of pluripotency of cells were also investigated. RESULTS: C5A cells prepared from PC-3 cell-derived sphere culture expressed pluripotency markers such as Oct4, Sox2, and Klf4. C5A cells were highly proliferative. They were invasive in vitro and tumorigenic in vivo. Some dopamine receptor antagonists such as thioridazine caused reduction of pluripotency markers and tumorigenicity. Thioridazine, unlike promazine, inhibited phosphorylation of AMPK in a dose dependent manner. BML-275, an AMPK inhibitor, also induced differentiation of C5A cells as seen with thioridazine whereas A769663, an AMPK activator, blocked its differentiation-inducing ability. Transfection of C5A cells with siRNAs of dopamine receptor subtypes revealed that knockdown of DRD2 or DRD4 induced morphology changes of C5A cells. CONCLUSIONS: Some dopamine receptor antagonists such as thioridazine can induce differentiation of CSC-like cells by inhibiting phosphorylation of AMPK. Binding to DRD2 or DRD4 might have mediated the action of thioridazine involved in the differentiation of CSC-like cells.

Aligned Heterointerface-Induced 1T-MoS2 Monolayer with Near-Ideal Gibbs Free for Stable Hydrogen Evolution Reaction.

1T-phase molybdenum disulfide (1T-MoS2 ) exhibits superior hydrogen evolution reaction (HER) over 2H-phase MoS2 (2H-MoS2 ). However, its thermodynamic instability is the main drawback impeding its practical application. In this work, a stable 1T-MoS2 monolayer formed at edge-aligned 2H-MoS2 and a reduced graphene oxide heterointerface (EA-2H/1T/RGO) using a precursor-in-solvent synthesis strategy are reported. Theoretical prediction indicates that the edge-aligned layer stacking can induce heterointerfacial charge transfer, which results in a phase transition of the interfacial monolayer from 2H to 1T that realizes thermodynamic stability based on the adhesion energy between MoS2 and graphene. As an electrocatalyst for HER, EA-2H/1T/RGO displays an onset potential of -103 mV versus RHE, a Tafel slope of 46 mV dec-1 and 10 h stability in acidic electrolyte. The unexpected activity of EA-2H/1T/RGO beyond 1T-MoS2 is due to an inherent defect caused by the gliding of S atoms during the phase transition from 2H to 1T, leading the Gibbs free energy of hydrogen adsorption (ΔGH* ) to decrease from 0.13 to 0.07 eV, which is closest to the ideal value (0.06 eV) of 2H-MoS2 . The presented work provides fundamental insights into the impressive electrochemical properties of HER and opens new avenues for phase transitions at 2D/2D hybrid interfaces.

Multiple Heterojunction in Single Titanium Dioxide Nanoparticles for Novel Metal-Free Photocatalysis.

Despite a longstanding controversy surrounding TiO2 materials, TiO2 polymorphs with heterojunctions composed of anatase and rutile outperform individual polymorphs because of the type-II energetic band alignment at the heterojunction interface. Improvement in photocatalysis has also been achieved via black TiO2 with a thin disorder layer surrounding ordered TiO2. However, localization of this disorder layer in a conventional single TiO2 nanoparticle with the heterojunction composed of anatase and rutile has remained a big challenge. Here, we report the selective positioning of a disorder layer of controlled thicknesses between the anatase and rutile phases by a conceptually different synthetic route to access highly efficient novel metal-free photocatalysis for H2 production. The presence of a localized disorder layer within a single TiO2 nanoparticle was confirmed for the first time by high-resolution transmission electron microscopy with electron energy-loss spectroscopy and inline electron holography. Multiple heterojunctions in single TiO2 nanoparticles composed of crystalline anatase/disordered rutile/ordered rutile layers give the nanoparticles superior electron/hole separation efficiency and novel metal-free surface reactivity, which concomitantly yields an H2 production rate that is ∼11-times higher than that of Pt-decorated conventional anatase and rutile single heterojunction TiO2 systems.