Ozone treatment of graphitic carbon nitride with enhanced photocatalytic activity under visible light irradiation

Photocatalytic Applications of g-C3N4 Based on Bibliometric Analysis

To further understand the application of g-C3N4 in the field of photocatalysis, this study focuses on the visualization and analysis of articles in this field using VOSviewer and Citespace. These articles were analyzed in terms of number of articles, journals, authors, countries and keywords, respectively. The results show that there is little collaboration among the core authors in this field and insufficient cross-directional communication; the current applications of g-C3N4 are concentrated on hydrogen evolution, CO2 reduction and water treatment. The developing trend is in the direction of constructing Z-scheme structures, regulating the separation of photogenerated carriers and reducing the recombination rate, to which more and more attention is being paid. In the future, cross-directional communication among scholars can be strengthened to promote faster development of the field of photocatalytic applications of g-C3N4.

Surface modification induced construction of core-shell homojunction of polymeric carbon nitride for boosted photocatalytic performance

Surface modification has been considered a simple and effective strategy to enhance the photocatalytic activity of polymeric carbon nitride (CN), but resultant difference of energy band structures between the modified surface layer and the unmodified inside in the sample has always been neglected. Herein, maleoyl-modified CN (MaCN) was simply prepared via a dehydration reaction between CN and maleic acid, and exhibits enhanced charge separation, optical absorption, and thus photocatalytic hydrogen evolution activity, relative to the bulk CN. The surface modification causes variation of the band structure, suggesting the difference of band levels between the surface layer with maleoyl-modification and the inside without any modification in MaCN, and the surface layer and the inside with matched band levels form type-II core-shell homojunction to enhance the charge separation. This work expounds a conceptual framework of core-shell homojunction in surface-modified CN photocatalysts.

Direct growth of uniform carbon nitride layers with extended optical absorption towards efficient water-splitting photoanodes

A general synthesis of carbon nitride (CN) films with extended optical absorption, excellent charge separation under illumination, and outstanding performance as a photoanode in water-splitting photoelectrochemical cells is reported. To this end, we introduced a universal method to rapidly grow CN monomers directly from a hot saturated solution on various substrates. Upon calcination, a highly uniform carbon nitride layer with tuned structural and photophysical properties and in intimate contact with the substrate is obtained. Detailed photoelectrochemical and structural studies reveal good photoresponse up to 600 nm, excellent hole extraction efficiency (up to 62%) and strong adhesion of the CN layer to the substrate. The best CN photoanode demonstrates a benchmark-setting photocurrent density of 353 µA cm⁻² (51% faradaic efficiency for oxygen), and external quantum yield value above 12% at 450 nm at 1.23 V versus RHE in an alkaline solution, as well as low onset potential and good stability.

Photoelectrochemical cells (PEC) can convert sunlight and water directly to a hydrogen fuel. Here a robust metal-free carbon nitride-based layer is used as an efficient photoanode for water-splitting PEC.

Influences of Calcination Atmosphere on Nickel Catalyst Supported on Mesoporous Graphitic Carbon Nitride Thin Sheets for CO Methanation

Nickel (Ni) catalysts supported on mesoporous graphitic carbon nitride (mpg-C₃N₄) were synthesized through simple impregnation method with air and nitrogen calcination atmosphere for CO methanation. The effects of pretreatment gas on catalyst structure, surface characteristics, and Ni species reducibility were investigated. Under air-calcination condition, the increase in specific surface area of the catalyst can be ascribed to the creation of mesopores and exfoliation of bulk mpg-C₃N₄ to form thin sheets. However, excessive Ni content on the catalyst accelerated the decomposition of the mpg-C₃N₄ support during calcination. The catalysts calcined in nitrogen showed lower surface area and fewer number of pores compared to air-treatment. The Ni/mpg-C₃N₄ catalyst calcined in air with Ni loading 10% exhibited enhanced medium-temperature activity for CO methanation with 79.7% CO conversion and 73.9% CH₄ selectivity. This finding can be explained by the formation of mpg-C₃N₄ thin sheets, which increased the number of catalyst active sites. The CO methanation performance of Ni/mpg-C₃N₄ catalysts calcined in air was superior to those calcined in nitrogen. Interestingly, CO₂ formed by water-gas shift reaction at 320 °C also contributed to the overall methane formation through CO₂ methanation. Therefore, mpg-C₃N₄ thin sheets can be an interesting support for nickel catalyst for CO_x methanation.

Posttransplant Outcomes of Patients With Autosomal Dominant Polycystic Kidney Disease Versus Other Recipients: A 10-Year Report From South of Iran

OBJECTIVES

Autosomal dominant polycystic kidney disease is the most common hereditary disorder resulting in end-stage renal disease that can affect other organs besides kidneys. Extrarenal involvement may increase mortality and morbidity. Approximately 50% of patients with this disorder require renal transplant. Posttransplant complications have been reported to be equal in these patients versus other recipients. We conducted this study to determine and compare characteristics and outcomes of transplanted patients with this disease versus other recipients at the only transplant center in southern Iran.

MATERIALS AND METHODS

Detailed data of patients with autosomal dominant polycystic kidney disease were collected from medical records from the Shiraz Organ Transplantation Center. We also gathered data on a matched control group of transplant recipients who had end-stage renal disease due to other reasons, including other congenital kidney diseases and type 2 diabetes mellitus. Medical records of patients before and after transplant were reviewed. Statistical analyses were performed with SPSS software version 19 (Chicago, IL, USA).

RESULTS

We collected data from 2002 to 2012 on 101 patients with autosomal dominant polycystic kidney disease and 100 control patients, including 74 female (36.8%) and 127 male patients (63.2%). Average duration of pretransplant dialysis was 14.9 ± 10.3 months in study patients and 12.8 ± 8.1 months in control patients. Rejection rate was statistically greater in recipients with this disease (30 patients; 68%) versus controls (14 patients; 32%) (P = .010).

CONCLUSIONS

Short- and long-term survival rates of patients with autosomal dominant polycystic kidney disease were not statistically different from control patients. However, graft survival was significantly lower. In short- and long-term follow-up of autosomal dominant polycystic kidney disease patients, hemoglobin and hematocrit levels were slightly higher than those of the control group. Autosomal dominant polycystic kidney disease is not a risk factor for posttransplant diabetes mellitus.