Spatial decoupling of bromide-mediated process boosts propylene oxide electrosynthesis.

The electrochemical synthesis of propylene oxide is far from practical application due to the limited performance (including activity, stability, and selectivity). In this work, we spatially decouple the bromide-mediated process to avoid direct contact between the anode and propylene, where bromine is generated at the anode and then transferred into an independent reactor to react with propylene. This strategy effectively prevents the side reactions and eliminates the interference to stability caused by massive alkene input and vigorously stirred electrolytes. As expected, the selectivity for propylene oxide reaches above 99.9% with a remarkable Faradaic efficiency of 91% and stability of 750-h (>30 days). When the electrode area is scaled up to 25 cm2, 262 g of pure propylene oxide is obtained after 50-h continuous electrolysis at 6.25 A. These findings demonstrate that the electrochemical bromohydrin route represents a viable alternative for the manufacture of epoxides.

Bipyridine-Confined Silver Single-Atom Catalysts Facilitate In-Plane C-O Coupling for Propylene Electrooxidation.

The electrooxidation of propylene presents a promising route for the production of 1,2-propylene glycol (PG) under ambient conditions. However, the C-O coupling process remains a challenge owing to the high energy barrier. In this work, we developed a highly efficient electrocatalyst of bipyridine-confined Ag single atoms on UiO-bpy substrates (Ag SAs/UiO-bpy), which exposed two in-plane coordination vacancies during reaction for the co-adsorption of key intermediates. Detailed structure and electronic property analyses demonstrate that CH3CHCH2OH* and *OH could stably co-adsorb in a square planar configuration, which then accelerates the charge transfer between them. The combination of stable co-adsorption and efficient charge transfer facilitates the C-O coupling process, thus significantly lowering its energy barrier. At 2.4 V versus a reversible hydrogen electrode, Ag SAs/UiO-bpy achieved a record-high activity of 61.9 gPG m-2 h-1. Our work not only presents a robust electrocatalyst but also advances a new perspective on catalyst design for propylene electrooxidation.

Dynamically Reversible Interconversion of Molecular Catalysts for Efficient Electrooxidation of Propylene into Propylene Glycol.

For the electrooxidation of propylene into 1,2-propylene glycol (PG), the process involves two key steps of the generation of *OH and the transfer of *OH to the C═C bond in propylene. The strong *OH binding energy (EB(*OH)) favors the dissociation of H2O into *OH, whereas the transfer of *OH to propylene will be impeded. The scaling relationship of the EB(*OH) plays a key role in affecting the catalytic performance toward propylene electrooxidation. Herein, we adopt an immobilized Ag pyrazole molecular catalyst (denoted as AgPz) as the electrocatalyst. The pyrrolic N-H in AgPz could undergo deprotonation to form pyrrolic N (denoted as AgPz-Hvac), which can be protonated reversibly. During propylene electrooxidation, the strong EB(*OH) on AgPz favors the dissociation of H2O into *OH. Subsequently, the AgPz transforms into AgPz-Hvac that possesses weak EB(*OH), benefiting to the further combination of *OH and propylene. The dynamically reversible interconversion between AgPz and AgPz-Hvac accompanied by changeable EB(*OH) breaks the scaling relationship, thus greatly lowering the reaction barrier. At 2.0 V versus Ag/AgCl electrode, AgPz achieves a remarkable yield rate of 288.9 mmolPG gcat-1 h-1, which is more than one order of magnitude higher than the highest value ever reported.

Understanding the Effect of *CO Coverage on C-C Coupling toward CO2 Electroreduction.

Cu-based tandem nanocrystals have been widely applied to produce multicarbon (C2+) products via enhancing CO intermediate (*CO) coverage toward CO2 electroreduction. Nevertheless, it remains ambiguous to understand the intrinsic correlation between *CO coverage and C-C coupling. Herein, we constructed a tandem catalyst via coupling CoPc with the gas diffusion electrode of Cu (GDE of Cu-CoPc). A faradaic efficiency for C2+ products of 82% was achieved over a GDE of Cu-CoPc at an applied current density of 480 mA cm-2 toward CO2 electroreduction, which was 1.8 times as high as that over the GDE of Cu. Based on in situ experiments and density functional theory calculations, we revealed that the high *CO coverage induced by CO-generating CoPc promoted the local enrichment of *CO with the top adsorption mode, thus reducing the energy barrier for the formation of OCCO intermediate. This work provides an in-depth understanding of the surface coverage-dependent mode-specific C-C coupling mechanism toward CO2 electroreduction.

Facet-dependent electrooxidation of propylene into propylene oxide over Ag3PO4 crystals.

The electrooxidation of propylene into propylene oxide under ambient conditions represents an attractive approach toward propylene oxide. However, this process suffers from a low yield rate over reported electrocatalysts. In this work, we develop an efficient electrocatalyst of Ag3PO4 for the electrooxidation of propylene into propylene oxide. The Ag3PO4 cubes with (100) facets exhibit the highest yield rate of 5.3 gPO m-2 h-1 at 2.4 V versus reversible hydrogen electrode, which is 1.6 and 2.5 times higher than those over Ag3PO4 rhombic dodecahedra with (110) facets and tetrahedra with (111) facets, respectively. The theoretical calculations reveal that the largest polarization of propylene on Ag3PO4 (100) facets is beneficial to break the symmetric π bonding and facilitate the formation of C-O bond. Meanwhile, Ag3PO4(100) facets exhibit the lowest adsorption energies of *C3H6 and *OH, inducing the lowest energy barrier of the rate-determining step and thus accounting for the highest catalytic performance.

A Highly Efficient Metal-Free Electrocatalyst of F-Doped Porous Carbon toward N2 Electroreduction.

N2 electroreduction into NH3 represents an attractive prospect for N2 utilization. Nevertheless, this process suffers from low Faraday efficiency (FE) and yield rate for NH3 . In this work, a highly efficient metal-free catalyst is developed by introducing F atoms into a 3D porous carbon framework (F-doped carbon) toward N2 electroreduction. At -0.2 V versus reversible hydrogen electrode (RHE), the F-doped carbon achieves the highest FE of 54.8% for NH3 , which is 3.0 times as high as that (18.3%) of pristine carbon frameworks. Notably, at -0.3 V versus RHE, the yield rate of F-doped carbon for NH3 reaches 197.7 µgNH3 mg-1 cat. h-1 . Such a value is more than one order of magnitude higher than those of other metal-free electrocatalysts under the near-ambient conditions for NH3 product to date. Mechanistic studies reveal that the improved performance in N2 electroreduction for F-doped carbon originates from the enhanced binding strength of N2 and the facilitated dissociation of N2 into *N2 H. F bonding to C atom creates a Lewis acid site due to the different electronegativity between the F and C atoms. As such, the repulsive interaction between the Lewis acid site and proton H suppresses the activity of H2 evolution reaction, thus enhancing the selectivity of N2 electroreduction into NH3 .

Freeing the Polarons to Facilitate Charge Transport in BiVO4 from Oxygen Vacancies with an Oxidative 2D Precursor.

The BiVO4 photoelectrochemical (PEC) electrode in tandem with a photovoltaic (PV) cell has shown great potential to become a compact and cost-efficient device for solar hydrogen generation. However, the PEC part is still facing problems such as the poor charge transport efficiency owing to the drag of oxygen vacancy bound polarons. In the present work, to effectively suppress oxygen vacancy formation, a new route has been developed to synthesize BiVO4 photoanodes by using a highly oxidative two-dimensional (2D) precursor, bismuth oxyiodate (BiOIO3 ), as an internal oxidant. With the reduced defects, namely the oxygen vacancies, the bound polarons were released, enabling a fast charge transport inside BiVO4 and doubling the performance in tandem devices based on the oxygen vacancy eliminated BiVO4 . This work is a new avenue for elaborately designing the precursor and breaking the limitation of charge transport for highly efficient PEC-PV solar fuel devices.

Safety and Efficacy of Facial Fat Grafting Under Local Anesthesia.

BACKGROUND: Facial fat grafting under local anesthesia has been widely performed in outpatient departments and private settings in China. The present study aimed to evaluate the safety and efficacy of facial fat grafting under local anesthesia. METHOD: A retrospective study was conducted on 155 patients who underwent facial fat grafting. The clinical data were recorded. Preoperative and postoperative two-dimensional images were acquired to evaluate the effect of facial fat grafting on refining facial contouring, rejuvenation as well as deformity reconstruction. The complications were recorded to assess the safety of the approach. RESULT: All the facial fat grafting procedures were performed successfully under local anesthesia. A majority of the patients who underwent one or more sessions of facial fat grafting under local anesthesia were satisfied with the cosmetic results. No severe complications occurred in these patients. CONCLUSIONS: In the present study, remarkable and natural improvements of facial contouring, rejuvenation as well as deformity reconstruction were achieved with facial fat grafting in most patients. Thus, the procedures performed under local anesthesia by experienced surgeons are safe. LEVEL OF EVIDENCE IV: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Combination of propranolol and sclerotherapy for treatment of infantile parotid hemangiomas.

We aimed to evaluate the efficacy of combination of propranolol and sclerotherapy in treating parotid hemangiomas. Twenty-six parotid hemangiomas patients were subjected to combined treatment from January 2009 and June 2014. The effects of the therapy modality were evaluated. Nineteen patients were females and 7 were males. The median age of treatment initiation was 4.96 months. Twelve lesions were located on the left side parotid glands, while thirteen lesions affected the right side. One infant had bilateral lesions. One to six (average 2.04) injections were performed and the mean period for propranolol was 8.94 months. All the patients got satisfied aesthetic outcomes. No complications of propranolol or sclerotherapy occurred during the whole medication period. The study demonstrated that combination of propranolol and sclerotherapy was an effective and safe method for infantile parotid hemangiomas. Larger-scale studies should be performed to further investigate the long-term efficacy and results of the present combined method for infantile parotid hemangiomas.