Charged Active Sites Research Articles

Application of the Linear Interaction Energy Method to Nitric Oxide Synthase Structure-Based Inhibitor Design.

The overproduction of nitric oxide by neuronal nitric oxide synthase (nNOS) is associated with several neuropathological conditions. As a result, inhibition of nNOS is a desirable therapeutic goal while avoiding the inhibition of endothelial NOS (eNOS) given its essential role in maintaining cardiovascular tone. Designing inhibitors with high specificity for nNOS over eNOS is challenging given the close similarity in the active site structure of all mammalian NOS isoforms. Computational methods like free energy perturbation (FEP) and thermodynamic integration (TI) offer attractive avenues for rational drug design, but application of these methods to NOS is hindered by several challenges, including proper handling of highly charged inhibitors with diverse structures as well as computational expense. To address these issues, we present a simplified approach combining continuum dielectric generalized born (GB) solvent models with linear interaction energy (LIE) calculations. Our method demonstrates excellent agreement with experimental data for charged inhibitors targeting mammalian NOS isoforms (mNOS). Our results highlight the utility of the GB-LIE method as a promising tool for screening NOS inhibitors and potentially other protein targets with charged active sites and diverse inhibitor structures.

Boosting charge separation and active sites exposure by hollow S-scheme MoSe2/Fe2O3 heterojunction for enhanced photocatalytic peroxymonosulfate activation towards ciprofloxacin removal

Regulating the properties of heterogeneous catalyst for efficient peroxymonosulfate (PMS) activation to pollutants degradation remains a challenge in photo-assisted Fenton-like reaction (PF) system. In this study, the novel S-scheme MoSe2/Fe2O3 (H-FMS) heterojunction with hollow nanostructure was successfully developed as visible-light-driven PMS activator for removal of ciprofloxacin (CIP). The prepared H-FMS catalyst in PMS/H-FMS/light system exhibits outstanding photocatalytic performance for CIP degradation, achieving 95.92 % removal of 5 mg/L CIP in 30 min with 0.5 mM PMS. The construction of S-scheme heterojunction provides photoinduced carriers with longer lifetime and higher redox abilities, thus sufficient photogenerated carriers are supplied to directly activate PMS. Simultaneously, the hollow nanostructure possessing multiple light reflection and scattering behaviors further facilitates the utilization of visible light. More importantly, high concentration of photoinduced electrons with high reduction ability in MoSe2 is conducive to continuous exposure of Mo4+ active sites for PMS activation through cycling between transition metal valence states. Overall, effectively separated electron-hole pairs and continuously exposed transition metal active sites both contribute to efficient activation of PMS as well as multi-path generation of ROS, leading to significant improvement in CIP degradation. The results of quenching experiment, electron spin resonance (ESR) technology, liquid chromatography-mass spectrometry (LC-MS) and density functional theory (DFT) calculation confirm that both free radicals (SO4∙-, •OH and O2∙-) and non radicals (1O2 and h+) attack the active sites of CIP possessing high Fukui index, thus contributing to CIP degradation. This work would provide a novel insight for future development and application of photocatalytic PMS activation catalysts in water remediation.

Post-calcination as an effective approach to enhance adsorption of arsenic and antimony anions by Mg/Al layered double hydroxide-decorated spent coffee ground biochars: Role of charge properties and active sites

This study evaluated the effects of post-calcination on the charge properties and active sites of Mg/Al layered double hydroxide-decorated spent coffee ground biochars (LDHMgAl@SCGB) governing adsorption behaviors and mechanisms of arsenic (AsV) and antimony (SbV) anions from aqueous phases. Post-calcinated LDHMgAl@SCGB (PLDHMgAl@SCGB) exhibited higher adsorption capacities for AsV and SbV compared to spent coffee ground biochars (SCGB) and LDHMgAl@SCGB as post-calcination of LDHMgAl@SCGB enhanced the charge properties (surface zeta potential at pH 7.0: SCGB = −21.8 mV, LDHMgAl@SCGB = 28.5 mV, and PLDHMgAl@SCGB = 34.4 mV) and increased active sites by eliminating the anions (i.e., Cl− ions) and water molecules at its interlayers. The calculated kinetic, intra-particle diffusion, and isotherm parameters indicated that the chemisorption and intra-particle diffusion were mainly responsible for the adsorption of AsV and SbV by SCGB, LDHMgAl@SCGB, and PLDHMgAl@SCGB. Moreover, post-calcination of LDHMgAl@SCGB enhanced its selectivity toward AsV and SbV by reinforcing the electrostatic surface complexation via its improvement of charge properties. Since PLDHMgAl@SCGB exhibited the excellent reusability for the adsorption of AsV (reuse efficiency >63.6%) and SbV (reuse efficiency >52.1%), it can be concluded that post-calcination of LDHMgAl@SCGB is a promising method for improving the adsorption capacities for AsV and SbV in real water matrices.

Machine Learning Accelerated Identification of Bifunctional Active Sites in Metal-Organic Framework Derived Metal Oxide Heterostructures for High-Performance Zinc-Air Batteries

The demand for electrochemical energy storage (ESS) systems and their market size has drastically increased in many applications ranging from portable devices through electric vehicles to large-scale grid systems over the past decades. Yet, a more advanced ESS is required due to the safety issues and limited energy density of currently commercialized lithium-ion batteries (LIBs) for wide and matured applications. As a solution to this challenge, zinc-air batteries (ZABs) have gained tremendous attention due to their high energy density, low cost, environmental friendliness, and much lower fire risk characteristics. ZABs utilize oxygen from the atmosphere at their cathode during discharge, where the atmospheric oxygen is reduced to hydroxide via an oxygen reduction reaction (ORR). On the other hand, hydroxide is released as oxygen via oxygen evolution reaction (OER) during charge. The fact that oxygen is drawn directly from the air enables high gravimetric and volumetric energy densities of ZABs compared to those of commercial LIBs. However, the sluggish kinetics of the four-electron transfer steps in ORR and the mass transport of oxygen in OER remain major challenges for the practical application of ZABs. Meanwhile, precious metal-based catalysts such as Pt/C and RuO2 are known to have good catalytic activity towards ORR and OER. However, the integration of different catalysts into the same cathode is very difficult. Additionally, the high cost and natural scarcity of novel metals limit their usage for practical applications.We synthesized a bifunctional CoO/Mn3O4 heterostructure (CMH) OER/ORR electrocatalyst which was derived from metal-organic framework (MOF) for excellent activities in ZABs. The CMH cathode exhibited high ORR and OER performances, as demonstrated by the higher ORR current density than that of the Pt/C catalyst as well as the low OER overpotential exceeding those of the RuO2 catalyst. Remarkably, atomic structures of the CMH were elucidated using global optimization of genetic algorithm integrated with the machine learning force field. By adopting first-principles electronic structure calculations, we further revealed the charge transfer and active sites for both reactions in the identified heterojunction. Furthermore, assembling CMH cathode and Zn metal anode into a ZAB full-cell configuration achieves a ~5.5-fold higher energy density of 879 Wh kg-1 exceeding those of commercial lithium-ion batteries (LIBs), a high-discharge outstanding power density that is 1.39 times higher than novel metal catalysts, and robust cycle stability with negligible voltage decay which is far superior to that of benchmark Pt/C+RuO2 electrocatalysts.

Three-layered nanoplates and amorphous/crystalline interface synergism boost CO2 photoreduction on bismuth oxychloride nanospheres.

Structural features like 3D nano-size, ultrathin thickness and amorphous/crystalline interfaces play crucial roles in regulating charge separation and active sites of photocatalysts. However, their co-occurrence in a single catalyst and exploitation in photocatalytic CO2 reduction (PCR) remains challenging. Herein, nano-sized bismuth oxychloride spheres (BiOCl-NS) confining three-layered nanoplates (∼2.2 nm ultrathin) and an amorphous/crystalline interface are exclusively developed via intrinsic engineering for an enhanced sacrificial-reagent-free PCR system. The results uncover a unique synergism wherein the three-layered nanoplates accelerate electron-hole separation, and the amorphous/crystalline interface exposes electron-localized active sites (Bi-Ovac-Bi). Consequently, BiOCl-NS exhibit efficient CO2 adsorption and activation with the lowering of rate-determining-step energy barriers, leading to remarkable CO production (102.72 μmol g-1 h-1) with high selectivity (>99%), stability (>30 h), and apparent quantum efficiency (0.51%), outperforming conventional counterparts. Our work provides a facile structural engineering approach for boosting PCR and offers distinct synergism for advancing diverse materials.

A novel ion-responsive hydrogel based on quaternized chitosan and hydroxyethyl cellulose for high efficient chloride ion adsorption

Chloride removal is crucial for industrial wastewater discharge, seawater purification and concrete structure durability. In this study, a novel hydrogel with excellent chloride adsorption property was prepared and the adsorption capacity in relation to external pH and other ions was evaluated. The hydrogel was synthesized using a one-pot method with quaternized chitosan (HACC), hydroxyethyl cellulose (HEC), and carboxymethyl chitosan (CMC) as monomers. By adjusting the material compositions, we effectively modulated the microstructure and charge characteristics of hydrogel, achieving a balanced swelling ratio and optimal adsorption performance. The optimal process conditions were identified as 25 °C and a chloride ion concentration of 40 mmol L−1, achieving a maximum adsorption capacity of 1080 mg g−1. Isotherm modeling showed that the adsorption fits well with the Freundlich isotherm, suggesting multilayer adsorption. The quaternary ammonium groups serve as fixed positive charge sites or active adsorption sites, enabling the hydrogel to efficiently adsorb anions through the synergistic effects of electrostatic interactions, physical adsorption, and amino protonation. The varied adsorption capacities of quaternary ammonium groups for different anions give rise to competitive adsorption phenomena among them. The incorporation of silver ions into the hydrogel greatly enhances its selective adsorption of chloride ions through chemical combination. This work presents a comprehensive strategy for designing a novel hydrogel with exceptional adsorption properties specifically tailored for chloride ions.

Bi2O3/MoO3 composites: A synergistic approach towards photocatalytic degradation and enhanced antimicrobial activity

The escalating concerns over the water containments and public health pose the great threat to sustainable environment. In this quest there is strong need of advance materials with sustainable solutions that provides the innovative methods for wastewater treatment. This article explores an in-depth study of synergistic effect of composites for photo degradation of methyl orange (MO) and tetracycline (TC) along with the antimicrobial activity. The composites were synthesized through facile hydrothermal method with the weight concentration of 1%, 3%, 5%, 7% of MoO3 represented by BOMO-1, BOMO-3, BOMO-5 and BOMO-7 respectively. Enhanced photocatalytic reported attributed to efficient charge separation and active sites formation of composites. Moreover significantly improved antibacterial activity of nanostructures occurs because of hetrojunction formation. The synergistic potential of Bi2O3/MoO3 composites resulted the generation of Reactive oxygen species (ROS) which performs the redox reaction to improved their activities. Additionally the fabricated nanomaterials evaluated by different characterization to check their optical, structural, morphological and electronic properties. The dual functionality of Bi2O3/MoO3 makes it a promising material for wastewater treatment as well as environmental remediation. These results predict its widely use for advance catalysis and hydrogen evolution procedure in near future.

Bifunctional S-scheme Fe7S8/CuIn5S8 heterostructures with S-vacancies for boosted photocatalytic antibiotic degradation and hydrogen evolution

The reasonable designing, interfacial tuning and construction of S-scheme heterostructures offering high performance water pollutants treatment and energy production still remains challenging. Following the structure, band structure and interface function perspective, we prepared Fe7S8/CuIn5S8 heterostructures photocatalysts with sulfur vacancies for superior norfloxacin (NOR) degradation and hydrogen production under visible light. In particular, for optimal 30FS/CIS (30%Fe7S8/CuIn5S8), the H2 evolution was up to 35.6 mmol g−1 h−1 which was 11.5 times than pristine Fe7S8 with TEOA as sacrificial agent. The heterojunction could also show 98.7% degradation of NOR in 90 min under visible light. Interestingly, using NOR pollutant as sacrificial agent under synergistic conditions, 22.7 mmol g−1 h−1 H2 evolution and 98.9% degradation of NOR (in 45 min) was achieved. The significantly boosted photocatalytic pollutant degradation and hydrogen generation performance over Fe7S8/CuIn5S8 hybrids is ascribed to the efficient S-scheme charge transfer and active sites provided by sulfur vacancies (Vs). The deep electron transfer mechanism and the charge transfer efficiency were supported by in-situ XPS, UPS, electrochemical experiments and photoluminescence. Experimental results including scavenging tests and ESR findings provided the direct evidence of photogenerated holes and ●OH radicals for pollutant degradation and electrons in hydrogen generation. This work contributes to effective designing and developing high-activity visible light/solar light assisted heterojunction photocatalysts for realizing superior clean energy generation and pollutant degradation.

Untapped potential of food waste derived biochar for the removal of heavy metals from wastewater

The presence of heavy metals in water pose a serious threat to both public and environmental health. However, the advances in the application of low cost biochar based adsorbent synthesize from various feedstocks plays an effective role in the of removal heavy metals from water. This study implies the introduction of novel method of converting food waste (FW) to biochar through pyrolysis, examine its physiochemical characteristics, and investigate its adsorption potential for the removal of heavy metals from water. The results revealed that biochar yield decreased from 18.4 % to 14.31 % with increase in pyrolysis temperature from 350 to 550 °C. Likewise, increase in the pyrolysis temperature also resulted in the increase in the ash content from 39.87 % to 42.05 % thus transforming the biochar into alkaline nature (pH 10.17). The structural and chemical compositions of biochar produced at various temperatures (350, 450, and 550 °C) showed a wide range of mineralogical composition, and changes in the concentration of surface functional groups. Similarly, the adsorption potential showed that all the produced biochar effectively removed the selected heavy metals from wastewater. However a slightly high removal capacity was observed for biochar produced at 550 °C that was credited to the alkaline nature, negatively charged biochar active sites due to O-containing functional groups and swelling behavior. The results also showed that the maximum adsorption was recorded at pH 8 at adsorbent dose of 2.5 g L−1 with the contact time of 120 min. To express the adsorption equilibrium, the results were subjected to Langmuir and Freundlich isotherms and correlation coefficient implies that the adsorption process follows the Freundlich adsorption isotherm. The findings of this study suggest the suitability of the novel FW derived biochar as an effective and low cost adsorbent for the removal of heavy metals form wastewater.

Modulating positive charge sites generations and iron oxidation state transitions in FeP4/CoP/C p-n heterojunction toward efficient oxygen evolution

Promoting the formation of positive charge active sites and high oxidation state FeOOH in the heterojunction electrocatalyst can enhance its intrinsic activity for oxygen evolution reaction (OER). However, the current synthesis methods that can simultaneously achieve both properties remain a great challenge. In this work, a feasible strategy for concurrently promoting the generation of positive charge active sites and high oxidation state metal species by constructing a heterojunction between FeP4 and CoP is proposed. Specifically, the p-n heterojunction between FeP4 and CoP is constructed by pyrolysis of MIL88A@FeCoLDH prepared by introducing Co through cation exchange using MIL88A as a template. The experimental and density functional theory calculation analyses suggest the construction of p-n heterojunction can effectively modulate the electron structure, optimize the d-band center, induce the generation of strong space charge region, and shorten the bond length of Fe-O, thus promoting the formation of positive charge active sites and high active species FeOOH and the adsorption ability of oxygen-containing intermediates for enhancing the OER performance. Benefiting from the synergistic effect between positive charge active sites and FeOOH, the obtained FeP4/CoP/C electrocatalyst exhibits a low overpotential of 258 mV for the OER at a current density of 10 mA cm−2 and superior stability at 20 mA cm−2 for 52 h. This work gives insights into the charge regulation effect in the heterojunction for enhancing the OER catalytic activity and provides a general strategy for designing more efficient oxygen evolution electrocatalysts.

Sulfur-regulated CoSe2 nanowires with high-charge active centers for electrochemical nitrate reduction to ammonium.

Developing high-efficiency electrocatalysts for nitrate-to-ammonia transformation holds significant promise for the production of ammonia, a crucial component in agricultural fertilizers and as a carbon-free energy carrier. In this study, we propose a viable strategy involving sulfur doping to modulate both the microstructure and electronic properties of CoSe2 for nitrate reduction. This approach remarkably enhances the conversion of nitrate to ammonia by effectively regulating the adsorption capability of nitrogenous intermediates. Specifically, sulfur-doped CoSe2 nanowires (S-CoSe2 NWs) exhibit a peak faradaic efficiency of 93.1% at -0.6 V vs. RHE and achieve the highest NH3 yield rate of 11.6 mg h-1 cm-2. Mechanistic investigations reveal that sulfur doping facilitates the creation of highly charged active sites, which enhance the adsorption of nitrite and subsequent hydrogenation, leading to improved selectivity towards ammonia production.

Atomic-level insights of enhanced interfacial charge transfer and active sites on self-assembly p-p heterostructure based on BiVO4/SnO2 for highly selective NO2 sensing

Even though there are several reports on gas detectors, the issue that remains unaddressed is selective sensing. In this work, a selective sensor is made by using well-ordered spherical shape BiVO4 and self-assembled p-p heterojunctions based on BiVO4/SnO2 nanocomposites. The self-assembly of SnO2 NPs on the defect sites of BiVO4 can easily be seen by the FESEM and HRTEM images. XPS spectrums indicate that the nanocomposite shows more active sites to adsorb gas molecules. The sensing characteristics of BiVO4/SnO2 as well as pristine BiVO4 and SnO2 reveal the p-type characteristics and confirm the formation of p-p heterojunctions. The sensing performance of the self-assembled BiVO4/SnO2 thin film gas sensor has been significantly improved by incorporating SnO2 and the sensor response of the self-assembled BiVO4/SnO2 is 1.98 which is much higher than pure BiVO4 and SnO2 and the lowest detection limit (LOD) was found as 7.8 ppb. Various configurations for the different heterostructures of BiVO4/SnO2 have been analyzed by using density functional theory and the results of p-p heterostructure are quite analogous with the experimental results. Enhancement in the number of active sites by the addition of SnO2 was also observed in the DFT interpretation.

Deciphering the Space Charge Effect of the CoNiLDH/FeOOH n-n Heterojunction for Efficient Electrocatalytic Oxygen Evolution.

Space charge transfer is an effective strategy to regulate the electron density of narrow bandgap semiconductors for enhancing electrocatalytic activity. Herein, the CoNiLDH/FeOOH n-n heterojunction hollow nanocages structure is constructed. The hollow structure provides abundant catalytic active sites and enhances mass transfer. The space charge region in the n-n heterojunction significantly promotes the adsorption of OH- and electron transfer; and the built-in electric field accelerates the electron transport, optimizes the electronic structure during the catalytic reaction process, and ensures the stability of surface charged active center sites in the heterojunction. Thus, CoNiLDH/FeOOH delivers an excellent oxygen evolution reaction (OER) overpotential of 250mV to achieve a current density of 10mA cm-2 with a small Tafel slope of 60mV dec-1 , and superior electrocatalytic durability for 210h at a high current density. Density functional theory calculations further verify that the space charge effect and built-in electric field in the n-n heterojunction of CoNiLDH/FeOOH can improve the electron transfer and lower the adsorption energy of OH- and the reaction energy barrier of the rate-determining step. This work provides a new fundamental understanding of the space charge effect of semiconductor heterojunction during the electrocatalytic process for developing more efficient OER electrocatalysts.

Highly efficient and stable layered AgZnS@WS2 nanocomposite electrode as superior charge transfer and active redox sites for energy harvesting device

Transition metal dichalcogenides (TMDs) are considered to be excellent candidates in energy storage applications because of their 2D structure and astonishing electrochemical features. Still, the poor stability of these materials limits their way to becoming perfect supercapattery electrode materials. Therefore, researchers are synthesizing their hybrids with other electrode materials to minimize these drawbacks. Herein, the tungsten disulfide (WS2) nanosheets were combined with hydrothermally synthesized silver zinc sulfide (AgZnS) nanostructures to design a hybrid electrode material for high-performance energy storage devices with superior charge transfer and abundant active redox sites. The highly porous structure of AgZnS@WS2 was analyzed by BET which confirmed the enhancement in ion diffusion and the reversible redox mechanism. The composite was analyzed using SEM, XRD, RAMAN, and XPS to study its morphological, structural, and compositional properties. The effect of different electrolytes was studied to estimate the electrochemical characteristics. The AgZnS electrode, upon characterization in 1 M KOH, revealed the maximum specific capacity (Qs) of 1209.06 Cg−1 at 1.8 Ag−1. While the AgZnS@WS2 hybrid electrode exhibited the Qs of 2516.58 Cg−1 at the same current density (js) benefitting from the features of both materials. The AgZnS@WS2 hybrid electrode employed in a supercapattery revealed a maximum Qs of 388.8 Cg−1 at 1.2 Ag−1. The device delivered a maximum energy density of 86.4 Wh kg−1 and a notable power density of 4987.6 W kg−1. The superb 95 % cycle stability and strong electrochemical performance of AgZnS@WS2 are the results of the highly conductive structure and synergistic effect of hybrid material for high surface area with quick ion diffusion. The astonishing features of hybrid material are suitable and encouraging for its industrial applications as supercapattery electrode material.

Heterointerface of vanadium telluride and zinc iron telluride nanosheets for highly efficient hydrogen production via water and urea electrolysis

Interface design is a promising strategy for electrocatalysis to optimize charge transfer ability and active sites of a catalyst. Herein, interfacially coupled vanadium telluride and zinc iron telluride nanosheets are synthesized on nickel foam (VTe2@ZnFeTe/NF) by a facile hydrothermal method, which furnishes low overpotentials of 119/217 mV for the hydrogen evolution reaction (HER) and 240/300 mV for the oxygen evolution reaction (OER) at 20/50 mA cm−2 in potassium hydroxide. The alkaline and urea electrolyzer formed by VTe2@ZnFeTe/NF requires an operating voltage of 1.58 V and 1.46 V to yield a current density of 10 mA cm−2 respectively. Density functional theory analysis reveals that the superb activity of VTe2@ZnFeTe/NF is related to its optimal adsorption free energy, extended electroactive centers, excellent charge transfer ability, and reasonable density of states near the Fermi level. These findings provide new insights for the design of transition metal telluride heterointerfaces as catalysts for water and urea electrolyzers.

Preparation and Characterization of Silver Nanoparticles by Pulsed Laser Ablation and Investigation of their Effect on Bacteria

Synthesis of silver nanoparticles (AgNP) by pulsed liquid laser ablation (PLAL) produces AgNPs that are better suited for biological applications compared to those prepared by standard wet-chemical methods. These were mainly achieved by water ablation with pulse widths in the nanosecond range. In the case of surface NP activation, we previously detected a strong surface-enhanced Raman scattering (SERS) signal from such AgNPs. To do this, we dilute Colloid slightly with LiCl. These surface alterations may have an effect on the NPs' capability to combat bacteria. every time, AgNPs with a median diameter of under ten nm were created., that has been incontestible in alternative studies to be the optimum size for germicidal activity.. Furthermore, minimum restrictive concentration (MIC) values for LiCl-modified AgNPs fell inside a slender vary of 1.1-3.8 g/mL, creating them the foremost efficient. This result's believed to be explained by the metal surface's enhanced surface reactivity, which is brought on by the existence of charged active sites.

Hollow core-shell LDH@N-HCS/CN S-scheme photocatalyst with the enhanced visible-light activity

It is a great challenge to effectively increase the charge separation and active sites of earth-abundant graphitic carbon nitride (CN) semiconductors to improve the photocatalytic performance. Looking for a highly active cocatalyst has attracted attention because of their potential to resolve the issues of low charge separation and low specific surface area of CN. A core-shell cocatalyst composed of nitrogen doped hollow carbon spheres (N-HCS) as the core and LDH nanoplates as the photoactive shell has been designed to increase the pristine CN active sites and charge separation. N-HCS acted as the support for LDH nanoplates to prevent particle agglomeration and served as the fast electron transfer channels to enhance the photoinduced charge separation efficiency. The ternary nanocomposites exhibited superior activity for nonyl phenol and Acid Blue 92 degradation compared to the unmodified CN under the visible light. The optimized deposition of LDH@N-HCS (15 wt%) on the CN surface resulted in 7-fold higher activity than without the cocatalyst. The improved photocatalytic activity of the ternary composite compared to CN could be attributed to two factors: efficient electron-hole pair separation due to LDH nanoplates and CN interface, and the presence of the N-HCS as an electron collector. The porous hollow structure of the cocatalyst exposes the numerous surface-active sites that favor visible light photocatalytic performance and supplies multiple reflection of photons into the cavity, increasing the usage ratio of light. This work will supply a novel strategy to rationally fabricate a noble metal-free binary cocatalyst for efficient visible light activity.

Band engineering of non-metal modified polymeric carbon nitride with broad spectral response for enhancing photocatalytic CO2 reduction

The development of environmentally friendly, low-cost, and efficient catalysts is crucial for photocatalytic CO2 conversion, and polymeric carbon nitride (PCN) is a promising star material for balancing carbon transformation. However, the application of PCN in the field of photocatalytic CO2 reduction is limited by the narrow photoresponse range and slow carrier separation behavior. In this work, a co-polymerization strategy of glycolic acid and urea was adopted to construct a Brown PCN (Bro-PCN) with a Broad spectral response while realizing the introduction of oxygen element which can promote the reconstruction of the electronic structure. The result shows that the Bro-PCN exhibits excellent CO generation performance compared with pristine PCN, even in the spectral range greater than 700 nm, showing the ability to promote the conversion of CO2 to CO. Experimental characterizations and DFT calculation confirmed that the excellent photocatalytic CO2 conversion ability is attributed to the improvement of light absorption and the contribution of added sub-gap impurity states to charge separation behavior and active sites. Thus, this work offers a universal strategy and insights into the design of broad spectral responsive PCN materials in the field of photocatalytic CO2 reduction.

Oxygen-enriched porous carbon derived from acid washed and oxidized lignite via H3PO4 hydrothermal for high-performance supercapacitors

Lignite-based porous carbon with clustered pore structure, large specific surface area (SSA) and high oxygen content is prepared by H3PO4 hydrothermal followed by KOH activation, which uses Shengli lignite modified by acid washing followed with oxidization (OAWSL) as carbon precursor. A part of ash in lignite is removed and abundant oxygen-containing functional groups are introduced through HCl washing and H2O2 oxidation. H3PO4 introduces phosphorus into OAWSL and promotes the formation of pores, then plentiful micropores are further formed by KOH. The POPC-2, which shows the best performance, has a high SSA (2852 m2 g−1) and an oxygen content of 15.73 wt%, providing more charge capacity and active sites. In addition, the POPC-2 as an electrode for supercapacitors exhibits a high specific capacitance of 320 F g−1 at 1 A g−1 and 272 F g−1 at 30 A g−1 in a three-electrode system in 6 M KOH electrolyte. Futhermore, the symmetric supercapacitors based on POPC-2 also shows high specific capacitance of 390 F g−1 at 0.05 A g−1, an energy density of 10.75 Wh kg−1 and outstanding cycling stability with 88% of the initial capacitance retention after 25,000 cycles at 2 A g−1.

Crystal facet engineering of polar single crystal BiOCl with improved piezo-photocatalytic activity

It is an effective strategy to enhance the piezoelectric-photocatalytic activity of catalysts by purposefully exposing highly active crystal planes, but the controllable synthesis remains a challenge. In addition, it is also elusive how the crystal planes regulate the activity. In this work, BiOCl with selectively exposed (001) or (101) crystal planes was synthesized by a pot of hydrothermal method. The degradation properties of organic dyes with different exposed crystal planes under photocatalysis, piezoelectric catalysis and piezoelectric photocatalysis were investigated. In addition, it is also found that in the process of piezoelectric photocatalysis, the enrichment of reducing active centers also promotes the occurrence of catalytic reactions, and plays a greater role than small-plane charge separation. The BiOCl with a with high exposure (001) plane not only has a narrow bandgap, high charge separation efficiency, and a significant piezoelectric coefficient, but also is more prone to experience band bending under ultrasonic action, thus significantly enhancing the activity. The findings of this research will deepen our comprehension of the piezoelectric-photocoupler catalytic reactions of crystal plane regulation affecting planar charge separation and active sites.