Synergistic effect of atomically dispersed Cu species and Ti-defects for boosting photocatalytic CO2 reduction over hierarchical TiO2.

The photocatalytic water-mediated CO2 reduction reaction, which holds great promise for the conversion of CO2 into valuable chemicals, is often hindered by inefficient separation of photogenerated charges and a lack of suitable catalytic sites. Herein, we have developed a glycerol coordination assembly approach to precisely control the distribution of atomically dispersed Cu species by occupying Ti-defects and adjusting the ratio between Cu species and Ti-defects in a hierarchical TiO2. The optimal sample demonstrates a ∼4-fold improvement in CO2-to-CO conversion compared to normal TiO2 nanoparticles. The high activity could be attributed to the Ti defects, which enhance the photogenerated charge separation and simultaneously facilitate the adsorption of water molecules, thereby promoting the water oxidation reaction. Moreover, by means of in situ EPR and FTIR spectra, we have demonstrated that Cu species can effectively capture photogenerated electrons and facilitate the adsorption of CO2, so as to catalyze the reduction of CO2. This work provides a strategy for the construction of atomic-level synergistic catalytic sites and the utilization of in situ techniques to reveal the underlying mechanism.

Photocatalytic production of ethylene and propionic acid from plastic waste by titania-supported atomically dispersed Pd species.

Current chemical recycling of bulk synthetic plastic, polyethylene (PE), operates at high temperature/pressure and yields a complex mixture of products. PE conversion under mild conditions and with good selectivity toward value-added chemicals remains a practical challenge. Here, we demonstrate an atomic engineering strategy to modify a TiO2 photocatalyst with reversible Pd species for the selective conversion of PE to ethylene (C2H4) and propionic acid via dicarboxylic acid intermediates under moderate conditions. TiO2-supported atomically dispersed Pd species exhibits C2H4 evolution of 531.2 µmol gcat-1 hour-1, 408 times that of pristine TiO2. The liquid product is a valuable chemical propanoic acid with 98.8% selectivity. Plastic conversion with a C2 hydrocarbon yield of 0.9% and a propionic acid yield of 6.3% was achieved in oxidation coupled with 3 hours of photoreaction. In situ spectroscopic studies confirm a dual role of atomic Pd species: an electron acceptor to boost charge separation/transfer for efficient photoredox, and a mediator to stabilize reaction intermediates for selective decarboxylation.

Improved Visible-Light Photocatalytic H2 Evolution of G-C3N4 Nanosheets by Constructing Heterojunctions with Nano-Sized Poly(3-Thiophenecarboxylic Acid) and Coordinating Fe(III).

It is highly desirable to enhance the photogenerated charge separation of g-C3N4 by constructing efficient heterojunctions, especially with an additional organic constitution for solar-hydrogen conversion. Herein, g-C3N4 nanosheets have been modified controllably with nano-sized poly(3-thiophenecarboxylic acid) (PTA) through in situ photopolymerization and then coordinated with Fe(III) via the -COOH groups of modified PTA, forming an interface of tightly contacted nanoheterojunctions between the Fe(III)-coordinated PTA and g-C3N4. The resulting ratio-optimized nanoheterojunction displays a ~4.6-fold enhancement of the visible-light photocatalytic H2 evolution activity compared to bare g-C3N4. Based on the surface photovoltage spectra, measurements of the amount of •OH produced, photoluminescence (PL) spectra, photoelectrochemical curves, and single-wavelength photocurrent action spectra, it was confirmed that the improved photoactivity of g-C3N4 is attributed to the significantly promoted charge separation by the transfer of high-energy electrons from the lowest unoccupied molecular orbital (LUMO) of g-C3N4 to the modified PTA via the formed tight interface, dependent on the hydrogen bond interaction between the -COOH of PTA and the -NH2 of g-C3N4, and the continuous transfer to the coordinated Fe(III) with -OH favorable for connection with Pt as the cocatalyst. This study demonstrates a feasible strategy for solar-light-driven energy production over the large family of g-C3N4 heterojunction photocatalysts with exceptional visible-light activities.

A Z-Scheme Heterojunctional Photocatalyst Engineered with Spatially Separated Dual Redox Sites for Selective CO2 Reduction with Water: Insight by In Situ µs-Transient Absorption Spectra.

Solar-driven CO2 reduction by water with a Z-scheme heterojunction affords an avenue to access energy storage and to alleviate greenhouse gas (GHG) emissions, yet the separation of charge carriers and the integrative regulation of water oxidation and CO2 activation sites remain challenging. Here, a BiVO4 /g-C3 N4 (BVO/CN) Z-scheme heterojunction as such a prototype is constructed by spatially separated dual sites with CoOx clusters and imidazolium ionic liquids (IL) toward CO2 photoreduction. The optimized CoOx -BVO/CN-IL delivers an ≈80-fold CO production rate without H2 evolution compared with urea-C3 N4 counterpart, together with nearly stoichiometric O2 gas produced. Experimental results and DFT calculations unveil the cascade Z-scheme charge transfer and subsequently the prominent redox co-catalysis by CoOx and IL for holes-H2 O oxidation and electrons-CO2 reduction, respectively. Moreover, in situ µs-transient absorption spectra clearly show the function of each cocatalyst and quantitatively reveal that the resulting CoOx -BVO/CN-IL reaches up to the electron transfer efficiency of 36.4% for CO2 reduction, far beyond those for BVO/CN (4.0%) and urea-CN (0.8%), underlining an exceptional synergy of dual reaction sites engineering. This work provides deep insights and guidelines for the rational design of highly efficient Z-scheme heterojunctions with precise redox catalytic sites toward solar fuel production.

Improving CO2 photoconversion with ionic liquid and Co single atoms.

Photocatalytic CO2 conversion promises an ideal route to store solar energy into chemical bonds. However, sluggish electron kinetics and unfavorable product selectivity remain unresolved challenges. Here, an ionic liquid, 1-ethyl-3-methylimidazolium tetrafluoroborate, and borate-anchored Co single atoms were separately loaded on ultrathin g-C3N4 nanosheets. The optimized nanocomposite photocatalyst produces CO and CH4 from CO2 and water under UV-vis light irradiation, exhibiting a 42-fold photoactivity enhancement compared with g-C3N4 and nearly 100% selectivity towards CO2 reduction. Experimental and theoretical results reveal that the ionic liquid extracts electrons and facilitates CO2 reduction, whereas Co single atoms trap holes and catalyze water oxidation. More importantly, the maximum electron transfer efficiency for CO2 photoreduction, as measured with in-situ µs-transient absorption spectroscopy, is found to be 35.3%, owing to the combined effect of the ionic liquid and Co single atoms. This work offers a feasible strategy for efficiently converting CO2 to valuable chemicals.

Improved Performance of g-C3N4 for Optoelectronic Detection of NO2 Gas by Coupling Metal-Organic Framework Nanosheets with Coordinatively Unsaturated Ni(II) Sites.

Sensitive and selective optoelectronic detection of NO2 with g-C3N4 (CN) is critical, but it remains challenging to achieve ultralow concentration (ppb-level) detection. Herein, Ni metal-organic frameworks/CN nanosheet heterojunctions were successfully fabricated by the electrostatic induced assembly strategy and then treated by a post-alkali etching process for creating coordinatively unsaturated Ni(II) sites. The optimized heterojunction exhibits a record detection limitation of 1 ppb for NO2, well below that observed on pristine CN, and an outstanding selectivity over other gases, along with long-time stability (120 days) at room temperature. The resulting superior detection performance benefits from the enhanced charge transfer and separation of the closely contacted heterojunction interface and the favorable adsorption of NO2 by unsaturated Ni(II) as selective adsorption sites mainly by means of the time-resolved photoluminescence spectra and in situ X-ray photoelectron spectra. Moreover, the in situ Fourier transform infrared spectra and temperature-programmed desorption disclose that the promotion adsorption of NO2 depends on the strengthened interaction between NO2 and Ni(II) node sites at the aid of OH groups from unsaturated coordination. This work offers a versatile solution to develop promising CN-based optoelectronic sensors at room temperature.

Atomic-Level Regulated 2D ReSe2 : A Universal Platform Boostin Photocatalysis.

Solar hydrogen (H2 ) generation via photocatalytic water splitting is practically promising, environmentally benign, and sustainably carbon neutral. It is important therefore to understand how to controllably engineer photocatalysts at the atomic level. In this work, atomic-level engineering of defected ReSe2 nanosheets (NSs) is reported to significantly boost photocatalytic H2 evolution on various semiconductor photocatalysts including TiO2 , CdS, ZnIn2 S4 , and C3 N4 . Advanced characterizations, such as atomic-resolution aberration-corrected scanning transmission electron microscopy (AC-STEM), synchrotron-based X-ray absorption near edge structure (XANES), in situ X-ray photoelectron spectroscopy (XPS), transient-state surface photovoltage (SPV) spectroscopy, and transient-state photoluminescence (PL) spectroscopy, together with theoretical computations confirm that the strongly coupled ReSe2 /TiO2 interface and substantial atomic-level active sites of defected ReSe2 NSs result in the significantly raised activity of ReSe2 /TiO2 . This work not only for the first time realizes the atomic-level engineering of ReSe2 NSs as a versatile platform to significantly raise the activities on different photocatalysts, but, more importantly, underscores the immense importance of atomic-level synthesis and exploration on 2D materials for energy conversion and storage.

Controlled Synthesis of Nitro-Terminated Oligothiophene/Crystallinity-Improved g-C3N4 Heterojunctions for Enhanced Visible-Light Catalytic H2 Production.

It is highly desired to explore closely contacted polymer semiconductor/g-C3N4 heterojunction photocatalysts with promoted photogenerated-carrier separation and extended visible-light response for efficient visible-light-driven H2 production. Here, we first synthesized the nitro-terminated oligothiophene (OTh) by the controlled copolymerization of thiophene and 2-nitrothiophene monomers, then constructed the nitro-terminated oligothiophene/crystallinity-improved g-C3N4 (OTh/g-C3N4) heterojunctions by a grinding-induced combination strategy. The ratio-optimized 20OTh5/g-C3N4 shows highly efficient H2 production activity up to 3.63 mmol h-1 g-1 under visible-light irradiation, with ∼25.9-time enhancement compared to that of g-C3N4. As verified by time-resolved photoluminescence spectra, surface photovoltage spectra, and the fluorescence spectra related to •OH amounts, the improved photocatalytic activity is due to the promoted photogenerated-carrier transfer and separation in the heterojunctions and the expanded visible-light response. It is also confirmed that the controlled OTh chain length, improved g-C3N4 crystallinity, and tight interface contact dependent on the hydrogen bonds and N···S interactions between OTh and g-C3N4 are reasonable for enhanced photogenerated-carrier separation with the electron transfer from OTh to g-C3N4. This work illustrates a feasible strategy to construct efficient polymer semiconductor/g-C3N4 heterojunction photocatalysts for solar-light-driven H2 production.

Atomically Dispersed ZnN5 Sites Immobilized on g-C3 N4 Nanosheets for Ultrasensitive Selective Detection of Phenanthrene by Dual Ratiometric Fluorescence.

Ultrasensitively selective detection of trace polycyclic aromatic hydrocarbons (PAHs) like phenanthrene (PHE) is critical but remains challenging. Herein, atomically dispersed Zn sites on g-C3 N4 nanosheets (sZn-CN) are constructed by thermal polymerization of a Zn-cyanuric acid-melamine supramolecular precursor for the fluorescence detection of PHE. A high amount (1.6 wt%) of sZn is grafted in the cave of CN with one N vacancy in the form of unique Zn(II)N5 coordination. The optimized sZn-CN achieves a wide detection range (1 ng L-1 to 5 mg L-1 ), ultralow detection limit (0.35 ng L-1 , with 5-order magnitude improvement over CN), and ultrahigh selectivity toward PHE even among typical PAHs based on the built PHE-CN dual ratiometric fluorescence method. By means of in situ Fourier transform infrared spectroscopy, time-resolved absorption and fluorescence spectroscopy, and theoretical calculations, the resulting superior detection performance is attributed to the favorable selective adsorption of PHE on as-constructed atomic Zn(II)N5 sites via the ionic cation-π interactions (Znδ+ C2 δ- type), and the fluorescence quenching is dominated by the inner filter effect (IFE) from the multilayer adsorption of PHE at low concentrations, while it is done by the protruded photogenerated electron-transfer process, as well as IFE from the monolayer adsorption of PHE at ultralow concentration.

Construction of Ultrathin S-Scheme Heterojunctions of Single Ni Atom Immobilized Ti-MOF and BiVO4 for CO2 Photoconversion of nearly 100% to CO by Pure Water.

To rationally design single-atom metal-organic framework (MOF)-involving photocatalysts remains an ongoing challenge for efficient CO2 conversion. Here, cuppy microstructures, consisting of a Ti(IV)-oxo node and three linked carboxylic moieties, in the single-coordination-layer Ti2 (H2 dobdc)3 MOF (NTU-9) are exploited to immobilize abundant single Ni(II) sites (Ni@MOF). The coupling of Ni@MOF with BiVO4 (BVO) nanosheets by H-bonding-induced assembly process obtains wide-spectrum 2D heterojunctions. The optimal heterojunction exhibits competitive performance and enables around 66-fold CO2 conversion of that for BVO nanoparticles by pure water, with nearly 100% CO selectivity. The exceptional photoactivity is attributed to favorable S-scheme charge transfer from BVO to MOF then to single Ni(II) sites. Noteworthily, single Ni(II) sites anchored by the Ti(IV)-oxo node and vicinal carboxylic moieties serving as a unique local microenvironment (LME) are found to synergistically catalyze CO2 conversion. Specifically, the hydroxyl groups of carboxylic moieties can form H-bonds with CO2 to promote its adsorption on single Ni(II) sites, and also can provide accessible protons to facilitate H-assisted CO2 reduction. Moreover, the CO desorption and subsequent CO2 adsorption on single Ni(II) sites with LME is proved to be thermodynamically favored, and hence dominates the high CO selectivity. This work highlights the significance of modulating the LME of single atoms to rationally design photocatalysts for realizing carbon neutralization.

NiPS3 ultrathin nanosheets as versatile platform advancing highly active photocatalytic H2 production.

High-performance and low-cost photocatalysts play the key role in achieving the large-scale solar hydrogen production. In this work, we report a liquid-exfoliation approach to prepare NiPS3 ultrathin nanosheets as a versatile platform to greatly improve the light-induced hydrogen production on various photocatalysts, including TiO2, CdS, In2ZnS4 and C3N4. The superb visible-light-induced hydrogen production rate (13,600 µmol h-1 g-1) is achieved on NiPS3/CdS hetero-junction with the highest improvement factor (~1,667%) compared with that of pure CdS. This significantly better performance is attributed to the strongly correlated NiPS3/CdS interface assuring efficient electron-hole dissociation/transport, as well as abundant atomic-level edge P/S sites and activated basal S sites on NiPS3 ultrathin nanosheets advancing hydrogen evolution. These findings are revealed by the state-of-art characterizations and theoretical computations. Our work for the first time demonstrates the great potential of metal phosphorous chalcogenide as a general platform to tremendously raise the performance of different photocatalysts.

N-Rich Doped Anatase TiO2 with Smart Defect Engineering as Efficient Photocatalysts for Acetaldehyde Degradation.

Nitrogen (N) doping is an effective strategy for improving the solar-driven photocatalytic performance of anatase TiO2, but controllable methods for nitrogen-rich doping and associated defect engineering are highly desired. In this work, N-rich doped anatase TiO2 nanoparticles (4.2 at%) were successfully prepared via high-temperature nitridation based on thermally stable H3PO4-modified TiO2. Subsequently, the associated deep-energy-level defects such as oxygen vacancies and Ti3+ were successfully healed by smart photo-Fenton oxidation treatment. Under visible-light irradiation, the healed N-doped TiO2 exhibited a ~2-times higher activity of gas-phase acetaldehyde degradation than the non-treated one and even better than standard P25 TiO2 under UV-visible-light irradiation. The exceptional performance is attributed to the extended spectral response range from N-rich doping, the enhanced charge separation from hole capturing by N-doped species, and the healed defect levels with the proper thermodynamic ability for facilitating O2 reduction, depending on the results of ∙O2- radicals and defect measurement by electron spin resonance, X-ray photoelectron spectroscopy, atmosphere-controlled surface photovoltage spectra, etc. This work provides an easy and efficient strategy for the preparation of high-performance solar-driven TiO2 photocatalysts.

TiO2-Modulated tetra(4-carboxyphenyl)porphyrin/perylene diimide organic Z-scheme nano-heterojunctions for efficient visible-light catalytic CO2 reduction.

Developing efficient Z-scheme heterojunctions with wide visible-light responsive perylene diimide (PDI) is highly desired for CO2 conversion, while the effective charge transfer and separation are crucial. Herein, TiO2-modulated tetra(4-carboxyphenyl)porphyrin/perylene diimide (T-TP/PDI) organic nano-heterojunctions have been fabricated for CO2 reduction, in which TP and PDI are first assembled via π-π interactions between their similar 2D conjugate structures, and then the TiO2 nanoparticles (ca. 10 nm) are anchored as an energy platform through the carboxyl groups on TP. The optimal one exhibits a ∼10-fold enhancement in photocatalytic activity compared with the pristine PDI. Based on the time-resolved surface photovoltage responses, electron paramagnetic resonance signals, in situ diffuse reflectance infrared Fourier transform spectra and the amount evaluation of H2O2 as the water-oxidation intermediate, it is suggested that the exceptional photoactivity be ascribed to the accelerated charge transfer and separation resulting from the constructed Z-scheme nano-heterojunctions with intimate interfacial interactions and the introduced energy platform TiO2 oriented towards largely inhibiting the type-II charge transfer pathway. This work diversifies the strategies for constructing efficient organic Z-scheme heterojunctions, and provides insight into interface correlation among components.

Current advances on g-C3N4-based fluorescence detection for environmental contaminants.

The development of highly-sensitive fluorescence detection systems for environmental contaminants has become high priority research in the past years. Special attention has been paid to graphitic carbon nitride (g-C3N4)-based nanomaterials, whose unique and superior optical property makes them promising and attractive candidates for this purpose. It is necessary to enhance the current understanding of the various classes of g-C3N4-based fluorescence detection systems and their mechanisms, as well as find suitable approaches to improve detection performance for environmental monitoring, protection, and management. In this review, the recent progresses on g-C3N4-based fluorescence detections for environmental contaminants, mainly including their basic principles, mechanisms, applications, modification strategies, and conclusions, are summarized. A particular emphasis is placed on the design and development of modification strategies for g-C3N4 with the objective of improving detection performance. High photoluminescence quantum yield, tunable fluorescence emission characteristics, and strong adsorption capacity of g-C3N4 could ensure the ultrasensitivity and selectivity of fluorescence detection of environmental contaminants. Concluding perspectives on the challenges and opportunities to design highly efficient g-C3N4-based fluorescence detection system are intensively put forward as well.

A novel composite anode via immobilizing of Ce-doped PbO2 on CoTiO3 for efficiently electrocatalytic degradation of dye.

The exploitation of efficient electrocatalyst is significantly important for degradation of refractory organic pollutants. Herein, a novel Ti/CoTiO3/Ce-PbO2 composite electrocatalyst (abbreviated as CTO/CP) is successfully constructed via facile consecutive immersion pyrolysis and electro-deposition method and then systematically characterized by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), Fourier Transform infrared spectroscopy (FT-IR), energy dispersive spectroscopy (EDS) and near infrared chemical imaging (NIR-CI). Importantly, the electrochemical measurements demonstrate that the CTO/CP possesses numerous prominent properties such as lower charge transfer resistance, larger electroactive area, higher oxygen evolution potential than those of the pristine Ti/CoTiO3 (CTO) and Ti/Ce-PbO2 (CP). Thereby, the CTO/CP exhibits an enhanced electrocatalytic degradation performance with the degradation efficiency as high as 90.0% and COD removal rate of 88.3% at 180 min for the optimal CTO/CP (denoted as 10 layers of CTO and 1 h electrodeposition of CP), in which the ·OH is the major reactive species. Additionally, the optimal CTO/CP also shows a higher ICE/ACE together with lower EEC and desirable stability, universal applicability for many different dyes and reusability. Overall, this work offers a promising approach for enhancing the electrocatalytic properties of CTO via introducing CP.

Construction of Six-Oxygen-Coordinated Single Ni Sites on g-C3 N4 with Boron-Oxo Species for Photocatalytic Water-Activation-Induced CO2 Reduction.

The configuration regulation of single-atom photocatalysts (SAPCs) can significantly influence the interfacial charge transfer and subsequent catalytic process. The construction of conventional SAPCs for aqueous CO2 reduction is mainly devoted toward favorable activation and photoreduction of CO2 , however, the role of water is frequently neglected. In this work, single Ni atoms are successfully anchored by boron-oxo species on g-C3 N4 nanosheets through a facile ion-exchange method. The dative interaction between the B atom and the sp2 N atom of g-C3 N4 guarantees the high dispersion of boron-oxo species, where O atoms coordinate with single Ni (II) sites to obtain a unique six-oxygen-coordinated configuration. The optimized single-atom Ni photocatalyst, rivaling Pt-modified g-C3 N4 nanosheets, provides excellent CO2 reduction rate with CO and CH4 as products. Quasi-in-situ X-ray photoelectron spectra, transient absorption spectra, isotopic labeling, and in situ Fourier transform infrared spectra reveal that as-fabricated six-oxygen-coordinated single Ni (II) sites can effectively capture the photoelectrons of CN along the BO bridges and preferentially activate adsorbed water to produce H atoms to eventually induce a hydrogen-assisted CO2 reduction. This work diversifies the synthetic strategies for single-atom catalysts and provides insight on correlation between the single-atom configuration and reaction pathway.

Energy Platform for Directed Charge Transfer in the Cascade Z-Scheme Heterojunction: CO2 Photoreduction without a Cocatalyst.

A universal strategy is developed to construct a cascade Z-Scheme system, in which an effective energy platform is the core to direct charge transfer and separation, blocking the unexpected type-II charge transfer pathway. The dimension-matched (001)TiO2 -g-C3 N4 /BiVO4 nanosheet heterojunction (T-CN/BVNS) is the first such model. The optimized cascade Z-Scheme exhibits ≈19-fold photoactivity improvement for CO2 reduction to CO in the absence of cocatalysts and costly sacrificial agents under visible-light irradiation, compared with BVNS, which is also superior to other reported Z-Scheme systems even with noble metals as mediators. The experimental results and DFT calculations based on van der Waals structural models on the ultrafast timescale reveal that the introduced T as the platform prolongs the lifetimes of spatially separated electrons and holes and does not compromise their reduction and oxidation potentials.

Significantly Raised Visible-Light Photocatalytic H2 Evolution on a 2D/2D ReS2 /In2 ZnS4 van der Waals Heterostructure.

Owing to dwindling fossil fuels reserves, the development of alternative renewable energy sources is globally important. Photocatalytic hydrogen (H2 ) evolution represents a practical and affordable alternative to convert sunlight into carbon-free H2 fuel. Recently, 2D/2D van der Waals heterostructures (vdWHs) have attracted significant research attention for photocatalysis. Here, for the first time a ReS2 /In2 ZnS4 2D/2D vdWH synthesized via a facile physical mixing is reported. It exhibits a highly promoted photocatalytic H2 -evolution rate of 2515 µmol h-1 g-1 . Importantly, this exceeds that for pristine In2 ZnS4 by about 22.66 times. This, therefore, makes ReS2 /In2 ZnS4 one of the most efficient In2 ZnS4 -based photocatalysts without noble-metal cocatalysts. Advanced characterizations and theoretical computations results show that interlayer electronic interaction within ReS2 /In2 ZnS4 vdWH and atomic-level S active centers along the edges of ReS2 NSs work collaboratively to result in the boosted light-induced H2 evolution. Results will be of immediate benefit in the rational design and preparation of vdWHs for applications in catalysis/(opto)electronics.

Nitrate removal from low C/N wastewater at low temperature by immobilized Pseudomonas sp. Y39-6 with versatile nitrate metabolism pathways.

For solving the challenge in nitrate removal from low C/N wastewater at low temperature, Pseudomonas sp. Y39-6 was isolated and used in nitrate removal. It showed aerobic-heterotrophic denitrification with rate of 1.77 ± 0.31 mg/L·h and unusual aerobic-autotrophic nitrate removal (rate of 0.324 mg/L·h). The aerobic-autotrophic nitrate removal mechanisms were deep investigated by analyzing the nitrate removal process and genomic information. At aerobic-autotrophic condition, the strain Y39-6 could assimilate nitrate to amino acid (NO3- + PHA + CO2 â†’ C5H7O2N) with the carbon source from Polyhydroxyalkanoic acid (PHA) degradation and CO2 fixation. Flagella motivation, swarming activity and extracellular polymeric substances (EPS) production regulated Pseudomonas sp. Y39-6 forming biofilm. Carriers immobilized with Pseudomonas sp. Y39-6 were used in moving bed biofilm reactor (MBBR) and achieved 24.83% nitrate removal at C/N < 1 and 4 °C. Results of this study provided a practical way for nitrogen removal from low C/N wastewater in cold region.

Ultrathin Phosphate-Modulated Co Phthalocyanine/g-C3N4 Heterojunction Photocatalysts with Single Co-N4 (II) Sites for Efficient O2 Activation.

Realization of solar-driven aerobic organic transformation under atmospheric pressure raises the great challenge for efficiently activating O2 by tailored photocatalysts. Guided by theoretical calculation, phosphate groups are used to induce the construction of ultrathin Co phthalocyanine/g-C3N4 heterojunctions (CoPc/P-CN, ≈4 nm) via strengthened H-bonding interfacial connection, achieving an unprecedented 14-time photoactivity improvement for UV-vis aerobic 2,4-dichlorophenol degradation compared to bulk CN by promoted activation of O2. It is validated that more •O2 - radicals are produced through the improved photoreduction of O2 by accelerated photoelectron transfer from CN to the ligand of CoPc and then to the abundant single Co-N4 (II) catalytic sites, as endowed by the matched dimension, intimate interface even at the molecular level, and high CoPc dispersion of resulted heterojunctions. Interestingly, CoPc/P-CN also exhibits outstanding photoactivities in the aerobic oxidation of aromatic alcohols. This work showcases a feasible route to realize efficient photocatalytic O2 activation by exploiting the potential of ultrathin metal phthalocyanine (MPc) assemblies with abundant single-atom sites. More importantly, a universal facile strategy of H-bonding-dominating construction of MPc-involved heterojunctions is successfully established.