Porous Defect Research Articles

Enhanced performance of H-C3N2 monolayer as anode material for Li-ion batteries by phosphorus doping

Graphitic carbon nitride sheets (CxNy), which possess a two-dimensional structure similar to N-doped graphene, have been extensively studied as potential anode materials for ion batteries due to their high nitrogen content and porous defect sites that can serve as atomic storage sites for alkali metals. compared with most carbon nitride sheets, monolayer H-C3N2 has the characteristics of higher pyridinic nitrogen content and porosity, and can provide more Li adsorption sites, resulting in a superior theoretical capacity of 2791 mAh/g. However, the high diffusion barrier of 1.75 eV implies the low charge/discharge rate, which limits its application in lithium-ion batteries. Here, this paper demonstrates that doping P atoms in H-C3N2 (PC18N11) has some advantages for application in batteries. Specifically, monolayer PC18N11 exhibits excellent stability and conductivity, much higher theoretical specific capacity (3542 mAh/g). Moreover, PC18N11 exhibits metallic properties when Li-ion is adsorbed, the conductivity is improved, and the interaction between Li-ions will greatly reduce the diffusion barrier. These favorable properties indicate that P-doped H-C3N2 monolayer is a promising anode material for Li-ion batteries.

EARLY TO MID-TERM OUTCOMES OF THE CUSTOM-MADE 3D-PRINTED TRIFLANGE ACETABULAR COMPONENT (AMACE) IN COMPLEX REVISION HIP ARTHROPLASTY: LARGEST UK STUDY REPORTING THE COMBINED EXPERIENCE OF TWO TERTIARY REVISION CENTRES

Different techniques have been described to address massive bone loss of the acetabulum in revision hip surgery. aMace has gained popularity as it provides customization aiming to restore hip centre and provide good initial stability in cases of large non-contained defects. It takes into account quality of host bone. Its porous defect filling scaffold provides an excellent surface for osteointegration.Our aim was to assess the short and mid-term outcomes of patients who underwent revision surgery using aMace system.Ethical approval was obtained. A retrospective study included all patients who had aMace between June 2013 and October 2022 allowing for a minimum of 12-months follow-up. Patients’ demographics, indication, bone-loss severity, reconstruction details, re-operation, complications, mortality, pain and function were assessed.52 cases were performed by 13 surgeons with median 51 months follow-up. Median age was 72.7 years. 86.5% were female. Average BMI was 25.3. Average ASA grade was 3.65% were classified as Paprosky IIIB and 32% were IIIA.73% were found to have poor bone quality on CT. Main indication for aMace was massive bone loss/discontinuity secondary to aseptic loosening in 88.5%.77% underwent single-stage revision. 53.8% had 2 or more previous revisions. 71% underwent stem revision in the same setting. 77% received a dual mobility bearing.Re-operation rate was 5.7% for instability and femoral PPF. LLD was reported in 9.6%.Permanent Sciatic nerve palsy occurred in 3.8% of the cases.30-days mortality was 1.9%.Statistically significant post-op improvements in pain and mobility were reported (p<0.001). None of the acetabular components have been revised.Our study shows satisfactory surgical outcomes with a relatively low complication rate and significant pain and mobility improvements in the early to mid-term stages.We recommend these costly cases to be done in highly specialist centres adopting MDT approach.

A macro-mesoscopic constitutive model for porous and cracked rock under true triaxial conditions

The complex mechanical and damage mechanisms of rocks are intricately tied to their diverse mineral compositions and the formation of pores and cracks under external loads. Numerous rock tests reveal a complex interplay between the closure of porous defects and the propagation of induced cracks, presenting challenges in accurately representing their mechanical properties, especially under true triaxial stress conditions. This paper proposes a conceptualization of rock at the mesoscopic level as a two-phase composite, consisting of a bonded medium matrix and frictional medium inclusions. The bonded medium is characterized as a mesoscopic elastic material, encompassing various minerals surrounding porous defects. Its mechanical properties are determined using the mixed multi-inclusion method. Transformation of the bonded medium into the frictional medium occurs through crack extension, with its elastoplastic properties defined by the Drucker–Prager yield criterion, accounting for hardening, softening, and extension. Mori–Tanaka and Eshelby’s equivalent inclusion methods are applied to the bonded and frictional media, respectively. The macroscopic mechanical properties of the rock are derived from these mesoscopic media. Consequently, a True Triaxial Macro-Mesoscopic (TTMM) constitutive model is developed. This model effectively captures the competitive effect and accurately describes the stress-deformation characteristics of granite. Utilizing the TTMM model, the strains resulting from porous defect closure and induced crack extension are differentiated, enabling quantitative determination of the associated damage evolution.

Synthesis of 2D zeolitic imidazolate frameworks based on Co(II) and Pd(II): Effect of Pd(II) addition on the CO2 cycloaddition with epichlorohydrin

Carbon dioxide (CO2) cycloaddition with epoxide can yield value-added cyclic carbonates with 100 % atom efficiency. Moreover, zeolitic imidazolate frameworks (ZIFs) have emerged as promising catalysts for this reaction as their basic and acidic sites can effectively activate CO2 and epoxide molecules. Here, novel mixed-metal ZIFs containing Pd and Co ions (PdCo-ZIFs) that are linked by benzimidazole ligands were synthesized, after which their structures were comprehensively characterized. Despite the inherent two-dimensional nanosheet structure of Co-ZIF, PdCo-ZIFs exhibited a large surface area, with a hierarchical porous structure and profoundly increased active site concentrations (10–20 times higher than those of Co-ZIFs), exhibiting significantly increased catalytic activity toward CO2 cycloaddition. Additionally, the relationship between the catalytic activity and structural characteristics of ZIFs correlated, and the representative Pd2Co8-ZIF catalyst achieved a maximum product yield of 97.3 %, with a high turnover number (5754) and turnover frequency (479 h−1) for cyclic carbonates, attributed to the well-developed porous structure and defect sites that could not be observed in single-metal ZIF materials.

In-situ generated of interface nanoengineering to improve bifunctional electrocatalysts activity

The exploitation of efficient electrocatalysts is vital for zinc-air batteries (ZABs). Fe-based catalysts exhibit insufficient bifunctional activity and stability, impeding the further development of ZABs. Herein, an efficient bifunctional electrocatalyst (PFeNC@NiFe-LDH) is rationally constructed and designed through the pore-creating and in-situ-generated interface nanoengineering approach. In this process, in-situ Fe-modified framework material (Fe-ZIF-8) regulates intermetallic distance to prevent Fe atom agglomeration. Fe-ZIF-8 and activator are co-heated to enable a highly porous structure and single-atom catalyst (PFeNC). The porous defect sites in PFeNC can be served as nucleation centers to anchor NiFe-LDH nanosheet, reinforcing the stability of the complex and enhancing bifunctional catalytic activity. Benefiting from single-atoms dispersing, interface effect, hierarchical pore channel, and synergistic effect, the PFeNC@NiFe-LDH demonstrates eminent bifunctional oxygen electrocatalytic performance (ΔE = 0.66 V), high stability, and rapid kinetic process (73.1 mV dec-1) for oxygen reduction reaction(ORR)), far outperforming the commercial Pt/C + IrO2 benchmark (ΔE = 0.87 V). Furthermore, the PFeNC@NiFe-LDH as a ZABs air-electrode delivers prominent stability last 16 days. These results take a perspective to devise bifunctional composite catalysts with NiFe-LDH grown on carbon-based materials.

A comprehensive study on the influence of the scan pattern in two porosity levels and surface roughness on the fatigue behavior of laser powder bed fusion manufactured specimens made of steel H13

As a developing and immature technique, additive manufacturing (AM) shows some limitations: depending on material and process parameters so far, it usually results in parts with residual porosity, high residual stresses and a surface with a certain level of roughness. Due to its weaknesses and high production costs, AM is more preferably used when the fabricated parts have a high geometry complexity, the material used is very expensive, or the parts can offer additional performance. In order to allocate AM further in industry, a better understanding of the not well-investigated fatigue behavior is necessary. This work focuses on the influences of some general process parameters including laser power, scan speed, scan pattern and postmachining on the resulting fatigue properties of H13 tool steel specimens generated through powder bed fusion (PBF) technique. Results reveal that scan patterns influence fatigue properties by affecting the largest porous defect size and microstructure thus matrix strength. The degree of porosity or roughness resulting from the energy input and postmachining has a significant inferior impact on the fatigue strength. Neither porosity nor tensile properties show a single direct mathematic correlation with the fatigue properties.

Numerical investigation of block support structures with different dimension parameters in laser powder bed fusion of AlSi10Mg

Support structures are necessary for laser powder bed fusion (LPBF) especially when overhanging structures are fabricated. In this study, in order to understand the heat dissipation effect of the block support structures on the overhanging structures, a three-dimensional finite element model including the starting layer of the overhanging structure and the block support structures with different dimension parameters was established to numerically investigate the thermal behavior during the LPBF process. The results revealed that the support structures could dissipate the excessive heat of the melt pool in the starting layer, thus formed smaller melt pool and denser area. Different morphological characteristics of melt pool were observed at different positions above the support structures. Compared with increasing the thickness of the support structures, decreasing the distance of the support structures caused the obvious reduction of the average dimension of the melt pool. Samples and the block support structures with different dimension parameters fabricated by AlSi10Mg powder were also experimentally performed and the microstructures of the bottom section of the sample with starting and subsequent layers were investigated to verify the reliability of the numerical model. The minimum porous defect area was achieved at the optimal dimension parameters of the block support structures with 1.0 mm distance and 0.15 mm thickness.

Boron-doped g-CN monolayer as a promising anode for Na/K-ion batteries

Graphitic carbon nitride (CxNy) has a two-dimensional structure similar to N-doped graphene, which is nitrogen-rich and contains porous defect sites that can serve as atomic storage sites for alkali metals. Compared with C3N4, the most widely reported carbon nitride family, g-CN is structurally stable without graphitic nitrogen. However, the adsorption energy of Li/Na/K in the pore size is too negative (-2.60/-2.99/-3.11 eV) to be desorbed, and the high diffusion barrier of Li/Na/K ion (2.94/3.11/2.43 eV) implies the low charge/discharge rate for metal-ion batteries. Here, we showed that doping B atoms into the pore sites of g-CN (BC3N3) possess some advantages for application in batteries. Specifically, the BC3N3 monolayer has excellent stability, with moderate adsorption ability for Na/K (-0.54/-0.98 eV) and a much lower diffusion barrier of ion (0.73/0.35 eV). BC3N3 shows excellent theoretical specific capacity (603.30/904.95 mAh/g) and low average open-circuit voltage as an anode material for Na/K-ion batteries. Moreover, under a small amount of alkali metal adsorption, BC3N3 exhibits metallic properties and the electrical conductivity of BC3N3 is improved. These favorable properties indicate that the B-doped g-CN monolayer is a promising anode material for Na/K ion batteries and this approach can be extended to other porous carbon-nitrogen structures.

Synthesis and characterization of coal fly ash based multipurpose ultrafiltration membrane

In this work, coal fly ash was used as a major precursor to synthesize a multipurpose ceramic membrane by uniaxial compaction method. SEM, XRD and FTIR analysis were performed to identify the morphology, crystallinity and functional groups of the membrane. SEM image confirmed the porous structure and defect free membrane surface. XRD analysis revealed the existence of mullite, quartz and hematite crystalline phases. The minimum membrane sintering temperature was identified as 800 °C by Thermogravimetric analysis (TGA). The membrane porosity and average hydraulic pore radius were estimated as 39.8% and 41 nm, respectively. The membrane pure water flux increased from 2.09 to 11.31 m3/m2 sec while increasing the applied pressure from 69 to 483 kPa. A fixed concentration of Rhodamine B, Bovine Serum Albumin and Vanillin (50 mg/L) were tested with synthesized membrane to examine the separation performance at 207 kPa applied pressure. The separation efficiency of the ceramic membrane was in the order: Rhodamine B (95.2%) > Bovine Serum Albumin (92.8%) > Vanillin (39.4%). The results obtained in this study demonstrate that coal fly ash generated in thermal power plants could be effectively utilized to fabricate a multipurpose ultrafiltration membrane for different separation and purification applications in industries.

Organic dye-reformed construction of porous-defect g-C3N4 nanosheet for improved visible-light-driven photocatalytic activity

Porous graphitic carbon nitride (g-C3N4) nanosheet with controllable defect can provide high specific surface area, abundant active sites, improved charge separation and transport efficiency and optimized the photo-redox ability, which is considered as an attractive metal-free photocatalyst. However, purposeful design and construction of the porous-defective g-C3N4 nanosheets is still a challenge. Herein, we intentionally fabricated a unique organic dye-reformed melamine precursor towards the universal preparation of targeted porous-defect modified g-C3N4 nanosheets for improved visible-light-driven photocatalytic activity. As expected, the as-prepared g-C3N4 products synthesized from seven organic dyes (such as 4-nitrophenol, Rhodamine B, Rhodamine 6G, methyl orange, methylene blue, crystal violet and malachite green)-reformed melamine precursors can integrate the advantages of porous structure and defect simultaneously to obtain higher visible-light-driven photocatalytic degradation activities towards Rhodamine B dye solution. Undoubtedly, this organic dye-reformed melamine strategy for the synthesis of high-active g-C3N4 is universal and novel, which opens a new pathway for developing the efficient, economic and environmental-friendly photocatalysts.

Current advancements in friction stir welding of high density materials: A review

In today's industrial sector, welding seems to be a very essential procedure required for the manufacture and renovation of metal products. Scientists are continuously searching for the right forms of welding to be used for different joints. This growing interest will contribute to the use of dissimilar alloys that involve welding. Owing to energy efficiency and environmental friendliness, Friction stir welding (FSW), extremely efficient solid-state joining method, was being referred to as “green” technology. This is an emerging paradigm for joining metallic components, in specific compact high-strength alloys that have been known as non-weldable by conventional fusion welding. This is also recognized as being the most important breakthrough in the field of material integration over the last couple of decades. As in the current context, welding of metallic materials is substituted through FSW due to its special characteristics across fusion welding processes, i.e. lowered heat-affected zone (HAZ), significantly lower porous defect, eco-friendly, minimized distortion, no gas shielding requirement, etc. This review article provides a framework for engineers and designers to explore FSW for a broader variety of different materials. Applications, challenges as well as other factors relevant to FSW are also discussed to provide guidelines for the worldwide scientific community to undertake comprehensive research in this area. This review ends with suggestions for the future direction of study.

Novel broad-spectrum-driven g-C3N4 with oxygen-linked band and porous defect for photodegradation of bisphenol A, 2-mercaptophenthiazole and ciprofloxacin

Abundant active oxygen free radicals could efficiently remove refractory organic pollutants. In previous research, the original carbon nitride can form more hydrogen peroxide, however, owing to the limitation of its band structure, the original carbon nitride cannot decompose the hydrogen peroxide to generate more active oxygen free radicals. Herein, this work reports a simple bottom-up synthesis method, which synthesize a broad-spectrum-response carbon nitride (CN-CA) with oxygen-linked band and porous defect structure, while adjusting the band structure, and the introduction of the oxygen-linked band structure can also decompose the hydrogen peroxide produced by the original carbon nitride to form more active oxygen free radicals. Instrumental characterization and analysis of experimental results revealed the important role of oxygen-linked band and porous defects in adjusting the CN-CA energy band structure and improving its visible light absorption. The optimal CN-CA displays an outstanding photocatalytic degradation ability, that degradation rate of bisphenol A (BPA) reaches 99.8% within 150 min, the reaction rate constant of which is 6.77 times higher than that of pure g-C3N4, as also demonstrated with 2-mercaptophenthiazole (MBT) and ciprofloxacin (CIP). Meanwhile, the excellent degradation performance under blue LED (450–462 nm) and green LED (510–520 nm) exhibits the broad-spectrum characteristics of CN-CA. The degradation pathways of BPA and MBT were analyzed via HPLC-MS. Moreover, the primary active species were detected as O2−, OH and h+ based on the trapping experiments and ESR. This research provides a new strategy for g-C3N4 modified by porous defects and oxygen-linked band structure for environmental remediation.

A dual-template defective 3DOMM-TiO2-x for enhanced non-enzymatic electrochemical glucose determination

A defective three dimensionally ordered macro-mesoporous TiO2-X (3DOMM-TiO2-X) was successfully prepared through dual-template method and applied as non-enzymatic electrochemical glucose sensor. The introduced oxygen vacancies and Ti3+ defects through defect engineering, as well as the macro-mesoporous structure induced by dual template, synergistically improve the performance of glucose determination. The Nafion/3DOMM-TiO2-X/FTO electrode shows better current response to glucose than commercial P25 and 3DOM-TiO2. A two-stage wide detection linear range of 1 μM ~ 2.32 mM and 2.32 mM ~ 14.72 mM was observed, with the sensitivity of 14.11 μA mM−1 cm−2 and 3.44 μA mM−1 cm−2, detection limits of 0.15 μM and 0.63 μM (S/N = 3), respectively. The electrode also exhibits superior reproducibility, stability, and selectivity performance. Furthermore, a reactive oxygen species oxidation mechanism was proposed and investigated. The Nafion/3DOMM-TiO2-X/FTO electrode also exhibits the potential as a photoelectrochemical electrode. Our results indicate the feasibility of the strategies to enhance the sensing ability by improving electronic conductivity through constructing 3DOMM porous structure and defect engineering.

Investigation of the Effect of Artificial Internal Defects on the Tensile Behavior of Laser Powder Bed Fusion 17-4 Stainless Steel Samples: Simultaneous Tensile Testing and X-Ray Computed Tomography.

Insufficient data are available to fully understand the effects of metal additive manufacturing (AM) defects for widespread adoption of the emerging technology. Characterization of failure processes of complex internal geometries and defects in metal AM can significantly enhance this understanding. We aim to demonstrate a complete experimental measurement process and failure analysis method to study the effects of AM defects. We utilized simultaneous implementation of tensile tests with high-resolution X-ray computed tomography (XCT) measurements on 17-4 stainless steel dog-bone samples with an intentional octahedron-shaped internal cavity included in the gauge length and also containing much smaller lack-of-fusion (LOF) defects, all generated by a Laser Powder Bed Fusion (LPBF) additive manufacturing process. The LOF defects were introduced by intentionally changing the LPBF default processing parameters. XCT image-based linear elastic finite element (FE) simulations were used to interpret the data. The in-situ tensile tests combined with simultaneous XCT measurements revealed the details of the failure process initiated by additively manufactured rough internal surfaces and porous defect structures, which experienced high stress concentrations. Progressive collapse of ligaments leading to larger pores was clearly observed, and the resulting porosity evolution until failure was quantitatively analyzed. The high stress concentrations were also directly confirmed by the FE simulations. The experimental methods described in this paper enable the quantitative study of the complex failure mechanisms of additively manufactured metal parts, and the image-based FE simulation method is effective for identifying and/or confirming possible failure locations and features.

Novel broad-spectrum-driven oxygen-linked band and porous defect co-modified orange carbon nitride for photodegradation of Bisphenol A and 2-Mercaptobenzothiazole

Here, we successfully synthesized the oxygen-linked band and porous defect co-modified orange carbon nitride (AF-C3N4) using a simple method. Further, the band structure calculation of its simulated structure is performed by DFT, which shows that the introduction of oxygen-linked band can adjust its band structure. The photocatalytic degradation rates of 0.3AF-C3N4 for bisphenol A and 2-mercaptobenzothiazole were 8 times and 2.73 times that of the original g-C3N4, respectively. Moreover, 0.3AF-C3N4 also shows photocatalytic activity under different wavelength light (blue, green and red light), which indicates that the synthesized materials have a broad spectrum of photocatalytic activity. Further, we proposed a possible photocatalytic degradation pathway by HPLC-MS analysis. Free radical quenching test and ESR spectra show that the generated superoxide radicals (•O2−), hydroxyl radicals (•OH) and holes (h+) cause photodegradation, while enhancing singlet oxygen (1O2) and weaken the content of hydrogen peroxide has further proved that active oxygen groups play an important role in the photocatalytic degradation process. Additionally, the 0.3AF-C3N4 can also be a photoelectrochemical sensor to detect the concentration of bisphenol A (λ ≥ 550 nm). This study provides a new strategy for the synthesis of orange carbon nitride by oxygen-linked band and porous defect co-modification for photocatalytic applications.

Recent advances in carbon-based electrocatalysts for oxygen reduction reaction

Fuel cells are one of the most promising clean energy devices to substitute for fossil fuel in the future to alleviate energy crisis and environmental pollution. As the key reaction on the cathode in the fuel cells, oxygen reduction reaction (ORR) still requires efficient noble metal catalysts such as the commercial Pt/C to boost the reaction for its sluggish kinetics. Therefore, it is critical to design earth-abundant carbon-based catalysts with high efficiency and long-term stability to replace the noble metal-based catalysts. This review focuses on the recent progress about carbon-based ORR catalysts including non-metal doped carbon materials, transition metal-nitrogen-carbon species, transition metal carbides/carbon, single atom catalysts, and other carbon hybrids. And we further infer that the excellent ORR performances can be achieved by the balance of geometric and electronic structures of catalysts such as conductivity, surface area, hierarchical porous structure, defect and doping effect. Additionally, the perspective development trend is also proposed to guide the rational designation of carbon-based catalysts for ORR and even extend to other energy storage and conversion fields in the future.

Investigation on Template Etching Process of SBA‐15 Derived Ordered Mesoporous Carbon on Electrocatalytic Oxygen Reduction Reaction

AbstractOrdered mesoporous carbon (OMC) is a promising material for oxygen reduction reaction (ORR) in fuel cells owing to its high surface area and more number of catalytic active sites. Herein, OMC was synthesized by hard template method, i. e., nanocasting of sacrificial silica template (SBA‐15) and then the sacrificial template was abolished using three different etching chemicals namely, hydrofluoric acid (HF), sodium hydroxide (NaOH) and polyvinylidene fluoride (PVDF) respectively, in order to study the etching effect. The etched OMCs derived from the SBA‐15 template was confirmed by various characterization techniques. In OMC, the porous nature, surface morphology and defect density changes with respect to etching chemicals were evidently determined. From the electrochemical studies, it has been concluded that the NaOH etched OMC showed higher electrocatalytic activity than others by exhibiting more positive onset (0.83 V), half‐wave potential (0.75 V), high current density (3.3 mA/cm2), Tafel slope (83 mV/dec) and n‐value (2.4). Eventually, the electrochemical impedance study (EIS) was performed to determine the charge transfer resistance (Rct) of various etched OMCs and has been found that NaOH etched OMC shows the lowest Rct value due to the presence of more defective sites and result in enhancing oxygen adsorption during ORR.

WC1−x‐Coupled 3D Porous Defective g‐C3N4 for Efficient Photocatalytic Overall Water Splitting

Constrained by the limited visible light harvesting and high photogenerated electron‐hole pair recombination rate, pristine g‐C3N4 typically possesses poor overall water splitting behavior under visible light. To achieve efficient overall water splitting of g‐C3N4 without the assistance of precious metals, herein, a WC1−x‐coupled 3D porous defect g‐C3N4 is constructed through simple one‐step pyrolysis. Due to the introduction of platinum‐like WC1‐x, the effective heterogenization of WC1−x/g‐C3N4 greatly improves the charge separation. In the meanwhile, the 3D multiple microstructures established by the self‐protocol of ultrathin 2D g‐C3N4 nanosheets enhance the light absorption efficiency and optimize the separation of photoexcited carriers. Significantly, the generation of nitrogen defects is capable of bringing about an optimized band structure. Based on those modifications, a significant photocatalytic overall water splitting capacity under visible light is obtained without the sacrificial agent by the prepared 3D WC1−x/g‐C3N4, in which the simultaneous evolution of H2 and O2 was up to 84.1 and 41.7 µmol h−1 g−1, respectively.

Interaction of Components of Co-Sn and Co-Sn-Cu Powder Materials in Liquid Phase Sintering

The interaction of components and structure formation were studied in liquid phase sintering of Co-Sn and Co-Sn-Cu powder materials. The powders of commercially pure metals were mixed with an organic binder and applied on the steel substrate. Sintering was performed under vacuum at temperatures of 820 and 1100 °C. The structure of sintered alloys was investigated by X-ray diffractometry and electron probe microanalysis, and microhardness (HV0.01) of the structural components was measured. It has been found that the nature of interaction of the liquid tin with the solid phase at the initial stage of sintering affects the formation of structure and porosity of Co-Sn and Co-Sn-Cu alloys considerably. In Co-Sn alloys, diffusion of tin into cobalt particles leads to the formation of intermetallic compounds, which hinders spreading of the liquid phase. This results in a porous defect structure formed in Co-Sn alloys. In Co-Sn-Cu alloys, at the initial stage of sintering the liquid phase enriched with copper is formed that wets the cobalt particles and contributes to their regrouping. As a result of this, materials with minor porosity are formed.

One step to prepare Cl doped porous defect modified g-C3N4 with improved visible-light photocatalytic performance for H2 production and rhodamine B degradation

Cl doped porous defect modified graphitic carbon nitride (Cl-pdg-C3N4) have been synthesized by pyrolysis of the mixture of melamine and NH4Cl, and thoroughly analyzed by x-ray diffraction, Fourier transform infrared spectroscopy, x-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy, N2 adsorption-desorption isotherm, BET, UV–vis diffuse reflectance spectra, photoluminescence spectra and photoelectrochemical properties. Experimental results indicated that Cl in NH4Cl could react with melamine to form supermolecule to induce the formation of porous structure. Meanwhile, NH4Cl could occupy space to limit the long-range polymerization of g-C3N4, resulting in the formation of N defect. Moreover, NH4Cl as the Cl element precursor could induce Cl element doped in the g-C3N4 system. When Cl-pdg-C3N4 worked as photocatalyst for producing H2 and degrading rhodamine B under visible light, the as-prepared Cl-pdg-C3N4 presented more excellent photocatalytic activity and kept excellent recycled activity than bulk g-C3N4. Hence, this strategy provides insights into the fabrication of g-C3N4 with excellent photocatalytic activity, which was promisingly applied in various fields.