In Situ Fe/Co/B Codoped MoS2 Ultrathin Nanosheets Enable Efficient Electrocatalytic Nitrogen Reduction.

The development of sustainable and effective electrochemical nitrogen fixation catalysts is crucial for the mitigation of the terrible energy consumption resulting from the Haber-Bosch process. Molybdenum disulfide (MoS2) exhibits promise toward nitrogen reduction reaction (NRR) on account of its similar structure to natural nitrogenases MoFe-co but still undergoes serious challenges with unsatisfactory catalytic performance resulted from limited active sites, conductivity, and selectivity. In this work, Fe/Co/B codoped MoS2 ultrathin nanosheets are synthesized and verified as excellent NRR catalysts with high activity, selectivity, and durability. The FeCoB-MoS2 demonstrates a high ammonia yield of 36.99 µg h-1 mgcat-1 at -0.15 V vs RHE and Faraday efficiency (FE) of 30.65% at -0.10 V vs RHE in 0.1 M HCl. The experimental results and the density functional theory (DFT) calculations emphasize that codoping of Fe, Co, and B into MoS2 synergistically enhances its conductivity and optimizes the electronic structure of the catalyst, which significantly improves the electrocatalytic ammonia synthesis performance. This work broadens the potential and enlightens the strategy for designing efficient electrocatalysts in the NRR field.

Liquid Gallium-Assisted Pyrolysis of MOF Affording CNT Non-Hollow Frameworks in High Yields for High-Performance Sodium-Ion Battery Anode.

Carbon materials have great potential for applications in energy, biology, and environment due to their excellent chemical and physical properties. Their preparation by carbonization methods encounters limitations and the carbon loss during pyrolysis in the form of gaseous molecules results in low yield of carbon materials. Herein a low-energy (600 °C) and high-yield (82 wt.%) carbonization strategy is developed using liquid gallium-assisted pyrolysis of metal-organic frameworks (MOFs) affording the N-doped carbon nanotube (CNT) non-hollow frameworks encapsulating Co nanoparticles. The liquid gallium layer offers protection against air, promotes heat transfer, and limits the escape of small carbonaceous gaseous molecules, which greatly improve the yields of the pyrolysis reaction. Experimental and theoretical results reveal that the synergistic interaction between CNTs and N/O-containing groups gives a non-hollow framework composed of N/O-enriched and open CNTs (NOCNTF-15, 15 denotes the 15 mm thickness of the liquid gallium layer during the pyrolysis) with high specific capacity (185 mAh g-1 at 10 A g-1) and ultra-stable cyclability (stable operation at 10 A g-1 and 50 °C for 20 000 cycles). This study provides a unique approach to carbonization that facilitates the practical application of low-cost CNTs and other MOFs-derived carbon materials in high-performance sodium-ion batteries (SIBs).

Schottky Junction Enhanced Photosynthesis of Hydrogen Peroxide by Ultrathin Porous Carbon Nitride Supported Ni Nanoparticles.

Artificial photosynthesis for high-value hydrogen peroxide (H2O2) through a two-electron reduction reaction is a green and sustainable strategy. However, the development of highly active H2O2 photocatalysts is impeded by severe carrier recombination, ineffective active sites, and low surface reaction efficiency. We developed a dual optimization strategy to load dense Ni nanoparticles onto ultrathin porous graphitic carbon nitride (Ni-UPGCN). In the absence and presence of sacrificial agents, Ni-UPGCN achieved H2O2 production rates of 169 and 4116 µmol g-1 h-1 with AQY (apparent quantum efficiency) at 420 nm of 3.14% and 17.71%. Forming a Schottky junction, the surface-modified Ni nanoparticles broaden the light absorption boundary and facilitate charge separation, which act as active sites, promoting O2 adsorption and reducing the formation energy of *OOH (reaction intermediate). This results in a substantial improvement in both H2O2 generation activity and selectivity. The Schottky junction of dual modulation strategy provides novel insights into the advancement of highly effective photocatalytic agents for the photosynthesis of H2O2.

Theoretical study of transition metal-doped ß12 borophene as a new single-atom catalyst for carbon dioxide electroreduction.

The electrocatalytic carbon dioxide reduction reaction (CO2RR) presents a viable and cost-effective approach for the elimination of CO2 by transforming it into valuable products. Nevertheless, this process is impeded by the absence of exceptionally active and stable catalysts. Herein, a new type of electrocatalyst of transition metal (TM)-doped ß12-borophene (TM@ß12-BM) is investigated via density functional theory (DFT) calculations. Through comprehensive screening, two promising single-atom catalysts (SACs), Sc@ß12-BM and Y@ß12-BM, are successfully identified, exhibiting high stability, catalytic activity and selectivity for the CO2RR. The C1 products methane (CH4) and methanol (CH3OH) are synthesized with limiting potentials (UL) of -0.78 V and -0.56 V on Sc@ß12-BM and Y@ß12-BM, respectively. Meanwhile, CO2 is more favourable for reduction into the C2 product ethanol (CH3CH2OH) compared to ethylene (C2H4) via C-C coupling on these two SACs. More importantly, the dynamic barriers of the key C-C coupling step are 0.53 eV and 0.73 eV for the "slow-growth" sampling approach in the explicit water molecule model. Furthermore, Sc@ß12-BM and Y@ß12-BM exhibit higher selectivity for producing C1 compounds (CH4 and CH3OH) than C2 (CH3CH2OH) in the CO2RR. Compared with Sc@ß12-BM, Y@ß12-BM demonstrates superior inhibition of the competitive hydrogen evolution reaction (HER) in the liquid phase. These results not only demonstrate the great potential of SACs for direct reduction of CO2 to C1 and C2, but also help in rationally designing high-performance SACs.

Interfacial Electronic Interactions Between Ultrathin NiFe-MOF Nanosheets and Ir Nanoparticles Heterojunctions Leading to Efficient Overall Water Splitting.

Creating specific noble metal/metal-organic framework (MOF) heterojunction nanostructures represents an effective strategy to promote water electrolysis but remains rather challenging. Herein, a heterojunction electrocatalyst is developed by growing Ir nanoparticles on ultrathin NiFe-MOF nanosheets supported by nickel foam (NF) via a readily accessible solvothermal approach and subsequent redox strategy. Because of the electronic interactions between Ir nanoparticles and NiFe-MOF nanosheets, the optimized Ir@NiFe-MOF/NF catalyst exhibits exceptional bifunctional performance for the hydrogen evolution reaction (HER) (η10 = 15 mV, η denotes the overpotential) and oxygen evolution reaction (OER) (η10 = 213 mV) in 1.0 m KOH solution, superior to commercial and recently reported electrocatalysts. Density functional theory calculations are used to further investigate the electronic interactions between Ir nanoparticles and NiFe-MOF nanosheets, shedding light on the mechanisms behind the enhanced HER and OER performance. This work details a promising approach for the design and development of efficient electrocatalysts for overall water splitting.

Thermal evaporation-driven fabrication of Ru/RuO2 nanoparticles onto nickel foam for efficient overall water splitting.

Developing high-performance bifunctional electrocatalysts towards the hydrogen evolution reaction/oxygen evolution reaction (HER/OER) holds great significance for efficient water splitting. This work presents a two-stage metal-organic thermal evaporation strategy for the fabrication of Ru-based catalysts (Ru/NF) through growing ruthenium (Ru)/ruthenium dioxide (RuO2) nanoparticles (NPs) on nickel foam (NF). The optimal Ru/NF shows remarkable performance in both the HER (26.1 mV) and the OER (235.4 mV) at 10 mA cm-2 in an alkaline medium. The superior OER performance can be attributed to the synergistic interaction between Ru and RuO2, facilitating fast alkaline water splitting. Density functional theory studies reveal that the resulting Ru/RuO2 with the (110) crystal surface reinforces the adsorption of oxygen on RuO2, while metallic Ru improves water dissociation in alkaline electrolytes. Besides, Ru/NF requires only 1.50 V at 10 mA cm-2 for overall water splitting, surpassing 20 wt% Pt/C/NF||RuO2/NF. This work demonstrates the promising potential of a thermal evaporation approach for designing stable Ru-based nanomaterials loaded onto conductive substrates for high performance overall water splitting.

Titanium carbide sealed cadmium sulfide quantum dots on carbon, oxygen-doped boron nitride for enhanced and durable photochemical carbon dioxide reduction.

Despite great efforts that have been made, photocatalytic carbon dioxide (CO2) reduction still faces enormous challenges due to the sluggish kinetics or disadvantageous thermodynamics. Herein, cadmium sulfide quantum dots (CdS QDs) were loaded onto carbon, oxygen-doped boron nitride (BN) and encapsulated by titanium carbide (Ti3C2, MXene) layers to construct a ternary composite. The uniform distribution of CdS QDs and the tight interfacial interaction among the three components could be achieved by adjusting the loading amounts of CdS QDs and MXene. The ternary 100MX/CQ/BN sample gave a productive rate of 2.45 and 0.44 µmol g-1 h-1 for carbon monoxide (CO) and methane (CH4), respectively. This CO yield is 1.93 and 6.13 times higher than that of CdS QDs/BN and BN counterparts. The photocatalytic durability of the ternary composite is significantly improved compared with CdS QDs/BN because MXene can protect CdS from photocorrosion. The characterization results demonstrate that the excellent CO2 adsorption and activation capabilities of BN, the visible light absorption of CdS QDs, the good conductivity of MXene and the well-matched energy band alignment jointly promote the photocatalytic performance of the ternary catalyst.

Screening of Transition Metal Supported on Black Phosphorus as Electrocatalysts for CO2 Reduction.

The electrocatalytic CO2 reduction (CO2RR) is an effective and economical strategy to eliminate CO2 through conversion into value-added chemicals and fuels. However, exploring and screening suitable 2D material-based single-atom catalysts (SACs) for CO2 reduction are still a great challenge. In this study, 27 (3d, 4d, and 5d, except Tc and Hg) transition metal (TM) atom-doped black phosphorus (TM@BP) electrocatalysts were systematically investigated for CO2RR by density functional theory calculations. According to the stability of SACs and their effectiveness in activating the CO2 molecule, three promising catalysts, Zr@BP, Nb@BP, and Ru@BP, were successfully screened out, exhibiting outstanding catalytic activity for the production of carbon monoxide (CO), methyl alcohol (CH3OH), and methane (CH4) with limiting potentials of -0.79, -0.49, and -0.60 V, respectively. A catalytic relationship between the d-band centers of SACs and the limiting potential of CO2RR was used to estimate the catalytic activity of catalysts. Furthermore, Nb@BP has high selectivity for CO2RR to CH3OH compared to H2 formation, while the hydrogen evolution reaction significantly impacts the synthesis of CO and CH4 on Zr@BP and Ru@BP. Nitrogen atom doping in BP is beneficial for enhancing the selectivity of CO2RR, but it is detrimental to the activity of CO2RR. This study offers theoretical guidance for synthesizing highly efficient CO2RR electrocatalysts and further enhances structural modulation methods for layered 2D materials.

Revealing the elevation of Zn2+ in the brain of depressed mice by a ratiometric fluorescent probe with dual near-infrared emissions.

A mitochondria-targeted ratiometric fluorescent probe (Mito-Zn) was first designed and synthesized with dual emissions both located in the near-infrared region, for Zn2+ detection with high sensitivity and selectivity. By using the developed Mito-Zn, a high level of Zn2+ in the depressed mouse brain was discovered for the first time.

Single and double transition metal atoms doped graphdiyne for highly efficient electrocatalytic reduction of nitric oxide to ammonia.

The electrocatalytic conversion of nitric oxide (NORR) to ammonia (NH3) represents a pivotal approach for sustainable energy transformation and efficient waste utilization. Designing highly effective catalysts to facilitate the conversion of NO into NH3 remains a formidable challenge. In this work, the density functional theory (DFT) is used to design NORR catalysts based on single and double transition metal (TM:Fe, Co, Ni and Cu) atoms supported by graphdiyne (TM@GDY). Among eight catalysts, the Cu2@GDY is selected as a the most stable NORR catalyst with high NH3 activity and selectivity. A pivotal discovery underscores that the NORR mechanism is thermodynamically constrained on single atom catalysts (SACs), while being governed by electrochemical processes on double atom catalysts (DACs), a distinction arising from the different d-band centers of these catalysts. Therefore, this work not only introduces an efficient NORR catalyst but also provides crucial insights into the fundamental parameters influencing NORR performance.

Niobium Modification of CeO2 Tuning Electron Density of Nickel-Ceria Interfacial Sites for Enhanced CO2 Methanation.

CO2 methanation has attracted considerable attention as a promising strategy for recycling CO2 and generating valuable methane. This study presents a niobium-doped CeO2-supported Ni catalyst (Ni/NbCe), which demonstrates remarkable performance in terms of CO2 conversion and CH4 selectivity, even when operating at a low temperature of 250 °C. Structural analysis reveals the incorporation of Nb species into the CeO2 lattice, resulting in the formation of a Nb-Ce-O solid solution. Compared with the Ni/CeO2 catalyst, this solid solution demonstrates an improved spatial distribution. To comprehend the impact of the Nb-Ce-O solid solution on refining the electronic properties of the Ni-Ce interfacial sites, facilitating H2 activation, and accelerating the hydrogenation of CO2* into HCOO*, in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) analysis and density functional theory (DFT) calculations were conducted. These investigations shed light on the mechanism through which the activity of CO2 methanation is enhanced, which differs from the commonly observed CO* pathway triggered by oxygen vacancies (OV). Consequently, this study provides a comprehensive understanding of the intricate interplay between the electronic properties of the catalyst's active sites and the reaction pathway in CO2 methanation over Ni-based catalysts.

Radical-Based cis-Selective Annulations of N,N'-Cyclic Azomethine Imines with N-Sulfonyl Cyclopropylamines.

Azomethine imines, broadly known as 1,3-dipoles, efficiently produce synthetically and biologically significant dinitrogen-fused heterocycles via predominantly concerted or ionic pathways. Herein, we describe a radical-based annulation of azomethine imines utilizing visible-light photoredox catalysis for the first time. This strategy enables the synthesis of dinitrogen-fused saturated six-membered cyclic products that have traditionally been difficult to access. Notably, our process exhibits exceptional cis diastereoselectivity, controlled by the anomeric effect. Initial mechanistic investigations reveal a tandem process comprising intermolecular radical addition and intramolecular 6-exo-trig cyclization. This work illustrates potential within the realm of visible-light-driven radical cyclization reactions involving azomethine imines.

Developing Ni single-atom sites in carbon nitride for efficient photocatalytic H2O2 production.

Photocatalytic two-electron oxygen reduction to produce high-value hydrogen peroxide (H2O2) is gaining popularity as a promising avenue of research. However, structural evolution mechanisms of catalytically active sites in the entire photosynthetic H2O2 system remains unclear and seriously hinders the development of highly-active and stable H2O2 photocatalysts. Herein, we report a high-loading Ni single-atom photocatalyst for efficient H2O2 synthesis in pure water, achieving an apparent quantum yield of 10.9% at 420 nm and a solar-to-chemical conversion efficiency of 0.82%. Importantly, using in situ synchrotron X-ray absorption spectroscopy and Raman spectroscopy we directly observe that initial Ni-N3 sites dynamically transform into high-valent O1-Ni-N2 sites after O2 adsorption and further evolve to form a key *OOH intermediate before finally forming HOO-Ni-N2. Theoretical calculations and experiments further reveal that the evolution of the active sites structure reduces the formation energy barrier of *OOH and suppresses the O=O bond dissociation, leading to improved H2O2 production activity and selectivity.

In situ rapid synthesis of ionic liquid/ionic covalent organic framework composites for CO2 fixation.

IL/ICOF composites were in situ synthesized via a one-pot route in half an hour under ambient conditions for catalytic cycloaddition of CO2 with epoxides into cyclic carbonates. The prepared composites feature a decent CO2 adsorption capacity of 1.63 mmol g-1 at 273 K and 1 bar and exhibit excellent catalytic performance in terms of yield and durability. This work may pave a new way to design and construct functionalized porous organic frameworks as heterogeneous catalysts for CO2 capture and conversion.

In situ observation of a stepwise [2 + 2] photocycloaddition process using fluorescence spectroscopy.

Using highly sensitive and selective in situ techniques to investigate the dynamics of intermediates formation is key to better understand reaction mechanisms. However, investigating the early stages of solid-state reactions/transformations is still challenging. Here we introduce in situ fluorescence spectroscopy to observe the evolution of intermediates during a two-step [2 + 2] photocycloaddition process in a coordination polymer platform. The structural changes and kinetics of each step under ultraviolet light irradiation versus time are accompanied by the gradual increase-decrease of intensity and blue-shift of the fluorescence spectra from the crystals. Monitoring the fluorescence behavior using a laser scanning confocal microscope can directly visualize the inhomogeneity of the photocycloaddition reaction in a single crystal. Theoretical calculations allow us to rationalize the fluorescence behavior of these compounds. We provide a convenient strategy for visualizing the solid-state photocycloaddition dynamics using fluorescence spectroscopy and open an avenue for kinetic studies of a variety of fast reactions.

HOXD-AS2-STAT3 feedback loop attenuates sensitivity to temozolomide in glioblastoma.

AIMS: Glioblastoma multiforme (GBM) is the deadliest glioma and its resistance to temozolomide (TMZ) remains intractable. Long non-coding RNAs (lncRNAs) play crucial roles in that and this study aimed to investigate underlying mechanism of HOXD-AS2-affected temozolomide sensitivity in glioblastoma. METHODS: We analyzed and validated the aberrant HOXD-AS2 expression in glioma specimens. Then we explored the function of HOXD-AS2 in vivo and in vitro and a clinical case was also reviewed to examine our findings. We further performed mechanistic experiments to investigate the mechanism of HOXD-AS2 in regulating TMZ sensitivity. RESULTS: Elevated HOXD-AS2 expression promoted progression and negatively correlated with prognosis of glioma; HOXD-AS2 attenuated temozolomide sensitivity in vitro and in vivo; The clinical case also showed that lower HOXD-AS2 sensitized glioblastoma to temozolomide; STAT3-induced HOXD-AS2 could interact with IGF2BP2 protein to form a complex and sequentially upregulate STAT3 signaling, thus forming a positive feedback loop regulating TMZ sensitivity in glioblastoma. CONCLUSION: Our study elucidated the crucial role of the HOXD-AS2-STAT3 positive feedback loop in regulating TMZ sensitivity, suggesting that this could be provided as a potential therapeutic candidate of glioblastoma.

The construction of lattice-matched CdS-Ag2S heterojunction photocatalysts: High-intensity built-in electric field effectively boosts bulk-charge separation efficiency.

The built-in electric field of heterojunction can effectively promote carrier separation and transfer. While, its interface orientation is often random, leading to lattice mismatch and high resistance, thus limiting the efficiency of interfacial charge transfer. Herein, the lattice-matched heterojunction (CdS-Ag2S) was constructed by ion-exchange epitaxial growth. The results of surface photovoltage spectroscopy (SPV), transient photovoltage spectroscopy (TPV), and time-resolved photoluminescence (TRPL) show that the lattice-matched heterojunction has higher charge separation efficiency and longer photogenerated carrier lifetime than that of lattice-mismatched one. The lattice-matched CdS-Ag2S has a high built-in electric field (BIEF) value of 103.42 and a bulk-charge separation (BCS) efficiency of 68.71%, which is about three times higher than that of the lattice-mismatched heterojunction (CdS-Ag2S-M). In addition, the photodegradation efficiency of CdS-Ag2S towards norfloxacin (NOR) was also 3.4 times higher than that of CdS-Ag2S-M. The above results and density functional theory (DFT) calculations indicate that improving the lattice matching at the heterojunction is beneficial for establishing a high-intensity built-in electric field and effectively promoting bulk-charge separation efficiency, thus achieving excellent photocatalytic performance. This work provides an essential reference for the research of high-performance heterojunction photocatalysts.

Phase-Engineered Robust Cocatalyst of NiFe Bicarbonate with Pt Dopant for Enhanced Photocatalytic Water Splitting.

Exploring efficient cocatalysts capable of accelerating surface catalytic reaction is of great significance for the development of solar-driven hydrogen production. Herein, on the basis of NiFe hydroxide, we developed a series of Pt doped NiFe-based cocatalysts to promote the photocatalytic hydrogen production of graphitic carbon nitride (g-C3 N4 ). We find that the Pt doping can trigger phase reconstruction of NiFe hydroxide and lead to the formation of NiFe bicarbonate, which displays higher catalytic activity toward hydrogen evolution reaction (HER). The Pt doped NiFe bicarbonate modified g-C3 N4 shows excellent photocatalytic activity with H2 evolution rate up to 100 µmol/h, which is more than 300 times that of pristine g-C3 N4 . The experimental and calculation results demonstrate that the greatly improved photocatalytic HER activity of g-C3 N4 is not only due to the efficient carrier separation, but also attributed to the accelerated HER kinetics. Our work may provide guidance for designing novel and superior photocatalysts.

Recent advances in the theoretical studies on the electrocatalytic CO2 reduction based on single and double atoms.

Excess of carbon dioxide (CO2) in the atmosphere poses a significant threat to the global climate. Therefore, the electrocatalytic carbon dioxide reduction reaction (CO2RR) is important to reduce the burden on the environment and provide possibilities for developing new energy sources. However, highly active and selective catalysts are needed to effectively catalyze product synthesis with high adhesion value. Single-atom catalysts (SACs) and double-atom catalysts (DACs) have attracted much attention in the field of electrocatalysis due to their high activity, strong selectivity, and high atomic utilization. This review summarized the research progress of electrocatalytic CO2RR related to different types of SACs and DACs. The emphasis was laid on the catalytic reaction mechanism of SACs and DACs using the theoretical calculation method. Furthermore, the influences of solvation and electrode potential were studied to simulate the real electrochemical environment to bridge the gap between experiments and computations. Finally, the current challenges and future development prospects were summarized and prospected for CO2RR to lay the foundation for the theoretical research of SACs and DACs in other aspects.

Construction adsorption and photocatalytic interfaces between C, O co-doped BN and Pd-Cu alloy nanocrystals for effective conversion of CO2 to CO.

Photocatalytic reduction of carbon dioxide (CO2) into fuels is an auspicious route to alleviate the energy and environmental crisis brought by the continuous depletion of fossil fuels. The CO2 adsorption state on the surface of photocatalytic materials plays a significant role in its efficient conversion. The limited CO2 adsorption capacity of conventional semiconductor materials inhibit their photocatalytic performances. In this work, a bifunctional material for CO2 capture and photocatalytic reduction was fabricated by introducing palladium (Pd)-copper (Cu) alloy nanocrystals onto the surface of carbon, oxygen co-doped boron nitride (BN). The elemental doped BN with abundant ultra-micropores had high CO2 capture ability, and CO2 was adsorbed in the form of bicarbonate on its surface with the presence of water vapor. The Pd/Cu molar ratio had great impact on the grain size of Pd-Cu alloy and their distribution on BN. The CO2 molecules tended to be converted to carbon monoxide (CO) at interfaces of BN and Pd-Cu alloys due to their bidirectional interactions to the adsorbed intermediate species while methane (CH4) evolution might occur on the surface of Pd-Cu alloys. Owing to the uniform distribution of smaller Pd-Cu nanocrystals on BN, more effective interfaces were created in the Pd5Cu1/BN sample and it gave a CO production rate of 7.74 µmolg-1h-1 under simulated solar light irradiation, higher than the other PdCu/BN composites. This work can pave a new way for constructing effective bifunctional photo-catalysts with high selectivity to convert CO2 to CO.