Understanding the Poly (Triazine Imide) Crystals Formation Process: The Conversion from Heptazine to Triazine.

Poly (triazine imide) (PTI) generally obtained via ionothermal synthesis features extended π-conjugation and enhanced crystallinity. However, in-depth investigation of the polycondensation process for PTI is an onerous task due to multiple influencing factors and limited characterization techniques. Herein, to simplify the polymerization route and exclude non-essential factors, PTI was prepared by calcining only melamine and LiCl. This study aims to identify the pivotal role of LiCl in PTI formation, which can convert heptazine-based intermediates into more stable triazine-based PTI framework. Based on this discovery, we demonstrate the transformation process of the prepared samples from amorphous Bulk g-C3 N4 to regular PTI, and further prove that the reaction with LiCl causes disruption of heptazine covalent organic frameworks. Additionally, the PTI exhibits higher photocatalytic water splitting performance due to efficient charge carrier mobility and separation, as well as faster reaction kinetics. This discovery deepens understanding of the polycondensation process of PTI crystals and provides insights toward the rational design of crystalline carbon nitride-based semiconductors.

Photo-thermal Catalytic Hydrogenation of Halogenated Nitrobenzenes over Ni/P25 Catalyst.

As haloanilines (HANs) are important organic intermediates and fine chemicals, their preparation over non-noble-metal-based catalysts by catalytic hydrogenation has attracted wide attention. However, the reaction suffers from relatively harsh conditions. Herein, we found that a 3.5%Ni/P25 catalyst exhibited superior photo-thermal catalytic activity with a TOFs of 5207 h-1 for hydrogenation of p-chloronitrobenzene (p-CNB) to p-chloroaniline under a 300 W full spectrum, which was much higher than that of photo- and thermal catalysis alone. Moreover, the 3.5%Ni/P25 catalyst could be recycled 4 times and was effective for the hydrogenation of various halonitrobenzenes (HNBs) with superior selectivity. Furthermore, the kinetic research showed that the excellent catalytic performance could be attributed to the better activation and dissociation of H2 by photo-thermal catalysis and the hydrogenation of p-CNB obeyed the condensation routine by ionic hydrogenation over 3.5%Ni/P25.

The effect of doping and strain on superconductivity of T-graphene.

As an allotrope of graphene, T-graphene was predicted to be an intrinsic two-dimensional (2D) superconductor with a superconducting critical temperature (Tc) of about 20.8 K [Gu et al., Chin. Phys. Lett. 36, 097401 (2019)]. In this work, based on first-principles calculations, hole doping and biaxial tensile strain (BTS) are considered to modulate the electron-phonon coupling (EPC) and superconductivity of T-graphene. It is found that the EPC constant of T-graphene is 0.807 and the calculated critical temperature Tc is 28.2 K at a doping level of 0.5 hole per unit cell (3.31 × 1014 cm-2) and 12% BTS. Furthermore, when 0.8 hole per unit cell (5.43 × 1014 cm-2) doping and 10% BTS are applied, the EPC constant is 0.939, and the Tc can be boosted to 35.2 K, which is higher than those of the pristine T-graphene and many other 2D carbon-based superconductors.

Reinforcing Cd-S bonds through morphology engineering for enhanced intrinsic photocatalytic stability of CdS.

Effectively mitigating photocorrosion is paramount for achieving high-efficiency and sustainable hydrogen production through photocatalytic water splitting over CdS. In this work, we develop a morphology engineering strategy with adjustable Cd-S bond energy through a simple chemical bath deposition method to synthesize novel hollow hemispherical CdS (H-CdS). The morphologic structure CdS can be precisely controlled by adjusting the reaction temperature, time and pH. Compared with common morphologies of CdS, H-CdS, with its reinforced Cd-S bonding, exhibits not only improved photocatalytic hydrogen evolution activity (20.04 mmol/g/h) but also exceptional resistance to photocorrosion, resulting in outstanding cyclic stability even without the aid of cocatalysts or the introduction of other semiconductors. Comprehensive characterizations reveal that the photocorrosion resistance of H-CdS stems from the high Cd-S bond strength. Moreover, in-situ infrared spectroscopy confirms alterations in the properties and activities of the various CdS morphologies after photocatalytic reaction due to photocorrosion. We thoroughly describe the relationship among morphology, surface energy, bond energy and photocorrosion resistance. Our findings present a novel strategy for mitigating the photocorrosion of CdS and offer valuable insights for future research on CdS photocatalysts aimed at stable water splitting.

Diagnosis and Management of Giant Esophageal Fibrovascular Polyp With Hypopharyngeal Pedicle.

Background: Fibrovascular polyps (FVPs) with hypopharyngeal pedicles (hFVPs) are the rare intraluminal benign tumours of the upper aerodigestive tract, and their accurate diagnosis and optimal management are challenging. Purpose: The present retrospective study attempted to explore the optimal diagnosis and treatment of hFVPs. Research Design: The clinical records of 2 patients with giant, irregularly shaped hFVPs, who underwent several failed surgical procedures after inaccurate diagnosis, were reviewed. Finally, the patients were correctly diagnosed and successfully treated at Capital Medical University Beijing Friendship Hospital in different years, 2018 and 2020. Results: Case 1 was of a 43-year-old woman with 2 months of progressive dysphagia. Gastroenterologists overlooked the origin of her FVP, and decided to sever its narrowest point in the oesophagus through endoscopy. However, upon unsuccessful removal of the mass, a gastrotomy procedure was performed to extract the mass 7 days later. Symptoms recurred 3 months after the treatment, and a fibreoptic laryngoscopy confirmed hFVP in the patient at our department. A transcervical approach was used to sever the hypopharyngeal pedicle, achieve haemostasis and remove the oesophageal tumour. No recurrence was detected during the 2-year follow-up period after the treatment. Case 2 was of a 32-year-old man with dysphagia who had previously undergone transthoracic and transcervical oesophagotomy procedures within a gap of 3 months for the removal of FVP causing dysphagia. The hypopharyngeal pedicle was not diagnosed in the patient. The symptoms of dysphagia recurred 4 years after the treatment, and a fibreoptic laryngoscope confirmed hFVP at our department. The tumour was removed successfully through the transcervical approach. No recurrence was detected during the 6-months follow-up after surgery. Conclusion: In conclusion, the transcervical approach is suitable for achieving haemostasis and removing giant, irregularly shaped hFVPs.

A nickel-iridium alloy as an efficient heterogeneous catalyst for hydrogenation of olefins.

Nickel and iridium supported on SiO2 (Ni-Ir/SiO2) acted as an effective and reusable heterogeneous catalyst for hydrogenation of olefins, and it showed higher activity and selectivity than the monometallic counterparts. The Ni-Ir/SiO2 catalyst has small Ni-Ir alloy and monometallic Ni particles, and the high catalytic performance can be attributed to the isolated Ni atom in the Ni-Ir alloys.