Platinum (Pt)-based catalysts are the most widely used catalysts for the oxygen reduction reaction (ORR). However, there are still great challenges to overcome in improving catalyst activity and reducing the use of Pt. Herein, catalysts with Pt nanoparticles and metal oxide nanoparticles on N-doped carbon with ultralow Pt loading (<2 wt % Pt), namely, Pt&Fe2O3/NC and Pt&CoO/NC, are synthesized by a two-step pyrolysis method, in which N-doped carbon is first prepared by pyrolyzing carbon and melamine at 900 °C and Pt nanoparticles and metal oxide nanoparticles are then prepared by pyrolyzing a Pt salt and M(OH)x (M = Fe, Co) at 700 °C. The Pt and metal oxide are uniformly dispersed on the NC, resulting in ultrafine Pt nanoparticles (∼2 nm). Metal oxides regulate the electronic structure of Pt to weaken the binding energy of oxygen. Both Pt&Fe2O3/NC and Pt&CoO/NC show good ORR catalytic activities in alkaline solution. Pt&Fe2O3/NC shows the ORR catalytic performance, with the peak potential and half-wave potential at 0.883 and 0.862 V, better than those of Pt&CoO/NC (0.861 and 0.842 V) and Pt/NC (0.856 and 0.838 V) and comparable to that of commercial 20 wt % Pt/C. The ORR mechanism on these two catalysts involves a direct four-electron path. This provides a method for improving the ORR catalytic performance of catalysts with ultralow Pt loading via the joint anchoring of ultrafine Pt by metal oxides and NC, resulting in synergistic interactions.

Severe acute pancreatitis (SAP) is a serious inflammatory disease that is often associated with high mortality rate. It tends to trigger a cascade of systemic inflammation that causes damage to multiple organs, such as the lungs and kidneys. Currently, there is no effective treatment plan to reverse the progress of SAP. The occurrence and development of SAP are associated with oxidative stress (OS) and ferroptosis. In this study, the Ca/Fe-based nanozymes are used as multi-enzyme simulants, which can effectively remove the reactive oxygen species and regulate ferroptosis to prevent and treat SAP. Notably, we make two trials for prevention and treatment of SAP. Under the condition of good biocompatibility, the Ca/Fe-based nanozymes effectively reduce the levels of serum pancreatitis-related biomarkers and inflammatory factors which involved in local and systemic inflammatory response. Moreover, the Ca/Fe nanozymes significantly increase the level of ferroptosis regulator of glutathione peroxidase 4 (GPx4) and ferritin heavy chain 1 (FTH1) in pancreas. These results demonstrate that the Ca/Fe-based nanozymes not only alleviate SAP but also mitigate subsequent multi-organ damage, thus providing an effective strategy of Ca/Fe nanozymes for treating SAP-related disorders in clinical research.

Carbonized polymer dots (CPDs) have attracted great interest as a nanomaterial in biomedical applications, especially in imaging and photodynamic therapy (PDT). However, CPDs with an aggregation-induced effect for type I PDT has been rarely reported. In this work, N,N′-dimethylurea and citric acid were used as precursors to prepare CPDs (YCPDs) with aggregation-induced effect in one pot by the solvothermal method. The YCPDs have a yellow emission of 550 nm and a high quantum yield of 68%, which lays a solid foundation for cell imaging. In addition, YCPDs can produce •O2– under white light irradiation and obtain •OH through electron transfer or hydrogen atom abstraction. In vitro results show that YCPDs possess great cytocompatibility but exert severe cytotoxicity to HeLa cells with only 2% of cell viability when exposed to ultralow-power-intensity (2.5 mW/cm2) light irradiation. Therefore, YCPDs, as a promising type I PDT nanomaterial, have a great potential for cancer therapy.

Polymer composites based on polycarbonate (PC) and polyether ether ketone (PEEK) filled with single-walled carbon nanotubes (SWCNTs, 0.5–2.0 wt %) were melt-mixed to investigate their suitability for thermoelectric applications. Both types of polymer composites exhibited positive Seebeck coefficients (S), indicative for p-type thermoelectric materials. As an additive to improve the thermoelectric performance, three different ionic liquids (ILs), specifically THTDPCl, BMIMPF6, and OMIMCl, were added with the aim to change the thermoelectric conduction type of the composites from p-type to n-type. It was found that in both composite types, among the three ILs employed, only the phosphonium-based IL THTDPCl was able to activate the p- to n-type switching. Moreover, it is revealed that for the thermoelectric parameters and performance, the SWCNT:lL ratio plays a role. In the selected systems, S-values between 61.3 μV/K (PEEK/0.75 wt % SWCNT) and −37.1 μV/K (PEEK/0.75 wt % SWCNT + 3 wt % THTDPCl) were reached. In order to shed light on the physical origins of the thermoelectric properties, the PC-based composites were studied using ultrafast laser time-resolved transient absorption spectroscopy (TAS). The TAS studies revealed that the introduction of ILs in the developed PC/CNT composites leads to the formation of biexcitons when compared to the IL-free composites. Moreover, no direct correlation between S and exciton lifetimes was found for the IL-containing composites. Instead, the exciton lifetime decreases while the conductivity seems to increase due to the availability of more free-charge carriers in the polymer matrix.

Despite numerous advantages over the traditional light absorbing materials, colloidal cesium lead halide (CsPbX3, X = Cl, Br, or I) perovskite nanocrystals (NCs) suffer from enormous defect density, leading to shorter lifetime of charge carriers and material instability. A large number of positively and negatively charged ionic defects are inevitably formed from crystallization via high temperature. Herein, we have studied a simple post-synthesis defect passivation of blue emitting CsPbCl3 NCs using monovalent metal ion LiCl as a dual-passivating agent. The observed effect (on optical properties) went up by leaps and bounds. Photoluminescence (PL) quantum yield increases from 2.8 to 47.6%, while PL life time increases from 0.56 to 20.79 ns. Various other chloride salts (CaCl2, NH2Cl, KCl, and NaCl) and Li salts (LiBr and LiI) with different cation and anion combinations, respectively, did not give this effect. All these together with the enhanced overall stability of NCs suggest the synergistic effect of dual passivation and deep defect passivation that leads to significant suppression of non-radiative recombination. An X-ray photoelectron spectroscopy study also reveals that this simple strategy promotes simultaneous passivation of both defects (vacancies) formed from negatively (chlorine) and positively charged ions (lead) of CsPbCl3. Theoretical study and experimental analysis in this work, together delivers a perceptive understanding of cationic and anionic vacancy healing by LiCl in CsPbCl3 NCs, thus enhancing its utilization as efficient blue light emitters.

Post-Li batteries based on Na, K, Ca, and Mg offer compelling alternatives to Li ones, whose resources are scarce and unevenly distributed in the earth’s crust. However, the development of these forthcoming batteries is currently thwarted by the lack of cost-effective, nontoxic, and highly efficient anode materials. To tackle this challenge, we employed a comprehensive structure search using the minima hopping method, followed by density functional theory (DFT) calculations. Our search led to an as-yet-unobserved metallic C7N monolayer with a Haeckelite structure. This unique structure features a network of sp2-nitrogen-containing heptagon and pentagon rings that are arranged in a way that enforces metallic characteristics. As such, C7N outperforms widely known 2D anode materials such as graphene, MoS2, and black phosphorus because of its superior storage capacity, lower diffusion barriers, and higher open-circuit voltages. It achieves a remarkable storage capacity of 1366 mA h g–1 for Na/K and an impressive 2730 mA h g–1 for Ca. Detailed analyses of charge, elastic constants, and molecular dynamics simulations demonstrate that the C7N possesses a strong yet flexible covalent network with a volume change of 2–4% during full charge and discharge cycles, ensuring long-term stability and reliability. The robust network of C7N also allows it to maintain a flat and thermally stable surface at full metal coverage and high temperatures. These findings open up avenues for exploring the Haeckelite carbon-nitride family as a promising candidate for next-generation battery technologies.

The agglomeration of polyaniline (PANI) nanofillers in waterborne resins substantially reduces the long-term corrosion resistance of the resins. In this study, we use gum arabic (GA), a biological macromolecule, as a green stabilizer to prepare aqueous dispersions of GA–PANI nanofillers via chemical oxidative polymerization. The highly dispersed GA–PANI nanofillers are incorporated into waterborne epoxy (WEP) matrix and sprayed onto Q235 steel surface. The results show that the GA–PANI nanofillers exhibit excellent dispersion, stability, and compatibility in WEP, as evidenced through transmission electron microscopy and scanning electron microscopy of the cross-sectional morphology, water-absorption tests, and coating adhesion tests. An electrochemical test indicates that the 3.0 wt % GA–PANI/WEP coating displays remarkable corrosion resistance, with the value of impedance modulus in the low-frequency region (|Z|0.01Hz) remaining at 3.372 × 107 Ω cm2 after 60 days of immersion in a 3.5 wt % NaCl solution. This value is almost 1 order of magnitude higher than that of WEP. An X-ray photoelectron spectroscopy test confirms the presence of a corrosion product component on the coating/steel interface. Moreover, the GA–PANI nanofillers extend the penetration route of corrosive species and provide favorable adhesion and anodic protection.

NO2 is a very dangerous and toxic gas and is prone to cause acid rain in high humidity environments, so it is essential to prepare a real-time monitoring and humidity immunity NO2 sensor. WO3 nanomaterials are commonly applied to detect NO2, but their poor immunity to humidity is still a critical limitation for the application. ZnO-nanorod-decorated WO3 nanosheets coated with ZIF-71 (ZnO@ZIF-71/WO3) composites prepared by an in situ growth method displayed excellent gas sensing performance and good humidity immunity to detect NO2. Compared to WO3 nanosheets and ZnO-nanorod-decorated WO3 nanosheets (ZnO/WO3) heterojunction composites grown on ceramic substrates in situ, ZnO@ZIF-71/WO3 presented excellent selectivity, good long-term stability, and a remarkably high response of about 947.96 to 100 ppm NO2 at 180 °C, which is 3.07 times higher than that of the ZnO/WO3 sensor and 4.59 times higher than that of the pure WO3 sensor. Even at a relative humidity of 85%, the response of ZnO@ZIF-71/WO3 to NO2 remained essentially constant. The functional ZIF-71 layer not only improved the humidity immunity of ZnO@ZIF-71/WO3 but also enhanced the sensitivity and selectivity performance to NO2 at low operating temperatures. The ZnO@ZIF-71/WO3 sensor still provided a response of 88.41 to 100 ppm NO2 at room temperature.

Cancer cell immune escape, metastasis, invasion, and recurrence are closely related to high immune-checkpoint expression and tumor hypoxia. Immune-checkpoint inhibition and tumor hypoxia regulation have therefore garnered attention in cancer therapeutics. This study found that the methyl pyropheophorbide-a (MPPa) derivative complex 31,32,7,8-tetrahydroxy-4H-MPPa-Cu2+ (HMPPa-Cu) induces apoptosis in tumor cells to activate immunogenicity. HMPPa-Cu combined with anti-programmed death ligand 1 (PD-L1) immune-checkpoint blockade (ICB) therapy not only eradicates light-irradiated primary CT26 colon cancer but also inhibits untreated distant tumors. HMPPa-Cu catalyzes hydrogen peroxide decomposition to generate oxygen in situ and increase the cellular oxygen concentration. To enable HMPPa-Cu tumor targeting and increase its cell uptake capacity, HMPPa-Cu was embedded with hyaluronic acid–cinnamaldehyde nanomicelles (NMs) to obtain HCHC NMs. Acid stimulation of the HCHC NMs released free HMPPa and Cu2+ and significantly increased the quantum yield of singlet oxygen. The tumor microenvironment and near infrared stimulation activated chemodynamic therapy (CDT) and photodynamic therapy (PDT) synergistically. Cu2+ depleted glutathione (DG) to amplify the reactive oxygen species and simultaneously underwent in situ oxygenation (ISO). HCHC NMs-mediated PDT/CDT/ISO/DG significantly improved the therapeutic effect of ICB.

UV irradiation on native graphene oxide (GO) surfaces in a cation-forming liquid yields surface cationic species that graft the reaction product directly on the GO surface. These surface cations also enhance the intrinsic photoluminescence of GO. The formation of pyrylium as the surface cation is proposed to be responsible for both effects. Using a micrometer-scale photomask, GO itself is used as a 2D platform to form chemical patterns by photoluminescence, cationic polymerization, and reactions with nucleophiles under UV or visible light exposure. Postpatterning by adsorption and fabricating a functionally graded surface are also described for further applications. Our finding offers a versatile light-exposure-based technique to mass-produce the GO microchips with a high integration density.

The development of radar technology has increased the possibility of warplanes being detected. Therefore, radar stealth capability is critical for warplanes. Currently, microwave-absorbing materials with plasticity are urgently needed to reduce the strong electromagnetic scattering from plenty of small gaps on aircraft. Here, we propose a strategy to encapsulate liquid metal with reduced graphene oxide (rGO) to form a plastic microwave-absorbing putty. The putty is formed by a self-assembly electrostatic method to create a sparse foam structure with good plasticity. Interestingly, the nonmagnetic putty not only shows a dielectric loss but also exhibits unique magnetic losses. This synergistic mechanism allows the putty to obtain a minimum reflection (RLmin) of −58.86 dB at 8.93 GHz with a small thickness of 3.57 mm. The excellent properties of this composite putty allow it to be a candidate for microwave-absorbing putties to reduce the radar cross section of airplanes.

Selective detection of toxic pollutants present in water has been a severe challenge to the scientific community for a long time. The noble integration of optical fiber-based interferometry with a bio-recognizing element molecular imprinting polymer (MIP) exhibits a promising technique for selective and susceptible biochemical detection. Here, we report a compact, stable, reproducible, and label-free optical sensor using a combined approach of photonic crystal fiber (PCF)-based modal interferometry and MIP nanoparticles (MIP-NPs) for selective detection of water pollutant p-cresol with an extremely low limit of detection (LOD). The MIP-NPs having a greater surface-to-volume aspect ratio allows more target analytes to bind. The sensor immobilized with MIP-NPs shows unprecedented sensitivity of 1.865 × 108 nm/M with specific and repeatable detection performance for a broad dynamic detection range of 10–8–10–3 M. The sensor offers a remarkable detection ability of as low as 1.55 nM concentrations of p-cresol in the aqueous medium, for water quality monitoring. Fast response, high resolution, compact size, label-free broad detection range, and selective reusable performance of the proposed sensor exhibit potential for board practical utilizations, including medical sectors, online and remote biosensing, and water resource monitoring.

Recently, novel two-dimensional materials, e.g., Xenes (graphdiyne, phosphorene, bismuthene, antimonene, etc.) and MXenes, have drawn great attention in nanophotonics due to their excellent flexibility, high photothermal conversion efficiency, and large thermal conductivity. Although the Xenes and MXenes have achieved rapid progress in many fields over the past decade, their relatively poor photodetection and nonlinear photonics have still limited their practical applications. In this work, a mixed-dimensional 2D MXene V2CTx nanosheet (NS)/0D bismuth quantum dot (Bi QD)-based heterostructure fabricated by a combination of selective etching and the hydrothermal method was simply deposited onto a clean poly(ethylene terephthalate) substrate with an embedded regular Ag lattice to prepare a flexible photoelectrochemical (PEC) electrode. The PEC result shows that the as-fabricated flexible electrode not only exhibits significantly improved photocurrent density (32.7 μA cm–2) and photoresponsivity (906 μA W–1) compared to individual MXene V2CTx NSs and Bi QDs but also displays high stability with a stable photocurrent density even after 200 bending cycles at 60°. Taking advantage of the Kerr effect of both MXene V2CTx NSs and Bi QDs, an all-optical switcher based on this mix-dimensional heterostructure for the spatial cross-phase modulation has also been realized with a preferred modulation depth. Density functional theory calculations provide direct evidence for the strong internal built-in electric field (7.3 × 107 eV m–1) created by the heterostructure for the enhancement of both photodetection and nonlinear photonics. The integration of Xenes or MXene-based mixed-dimensional heterostructures provides a concept and fundamental guidance to construct next-generation optoelectronic and photonic devices.

The development of highly efficient fixed catalysts is a significant concern in practical wastewater treatment using the peroxymonosulfate (PMS)-based Fenton-like process. In this study, we successfully synthesized a three-dimensional (3D) δ-MnO2 nanosheet (MNSN) net grown on a carbon-fiber (CF) sheet (3D-MNSN-CF) through a simple hydrothermal strategy. This novel catalyst demonstrated exceptional efficiency and stability in activating PMS for degrading refractory organics. The 3D-MNSN-CF catalyst was composed of wrinkled, ultrathin δ-MnO2 nanosheets (∼4.3 nm) grown on CF, forming a uniform 3D net structure with a covering thickness of approximately 7.6 μm (mass ratio ∼ 2.17%). This unique morphology provided a fixed Mn-based catalyst with a highly exposed (001) facet, intrinsic Mn3+/Mn4+ redox pair, and a high ratio of oxygen vacancies (OVs). These features enabled the 3D-MNSN-CF/PMS system to exhibit a remarkable removal ratio of approximately 100% for tetracycline hydrochloride (TC) degradation. The system also showed a high rate constant (k value) of approximately 0.15 min–1 and a specific activity (ε) of 3.46 L min–1 g–1 based on the MnO2 ratio, surpassing many reported Mn-based catalysts. Moreover, the 3D-MNSN-CF catalyst maintained excellent performance over a wide pH range from 2 to 11. Furthermore, we discovered that electron-rich oxygen-containing groups exhibited an inhibition effect by competing adsorption with PMS, hindering the generation of radicals. Additionally, the results indicated that singlet oxygen (1O2) was the main reactive species responsible for TC removal, while only a small amount of radicals contributed to the process. The catalyst’s excellent performance was also demonstrated in treating various refractory organics and real wastewater, and it exhibited splendid stability for recycling use.

Electrochemical supercapacitors (SCs) are high-efficiency electrochemical energy storage devices that can deliver energy at a very fast rate. Metal–organic framework (MOF)-derived layered double hydroxides (LDHs) are promising materials with great potential for commercial SC applications. In this study, a two-step synthetic strategy was developed to produce porous nanostructured ZnCoNi-LDH nanosheets (NSs) from bimetallic MOFs through a chemical reduction method. All the as-synthesized materials were characterized for their crystal structure, phase, morphology, and surface construction. The optimized ZnCo2Ni-LDH composition exhibited the best charge storage ability and specific capacitance among the different as-synthesized compositions. The specific capacitance of the fabricated device ZnCo2Ni-LDH||cellulose paper-KOH||ZnCo2Ni-LDH was found to be 348.2 F g–1 at 1.0 A g–1, with a maximum energy density of 54.4 W h kg–1 and a power density of 4439.0 W kg–1. After 10,000 continuous charge–discharge cycles, the device retained 86% of its capacitance. It also delivered a high-capacitance-specific Coulombic efficiency (57–60%). A mechanistic study corroborated the experimental results that the high pore volume, possible insertion of a greater number of electrolyte ions, multioxidation states of Ni and Co ions, and their synergistic effect with Zn2+ all contributed to the diffusion-controlled charge storage behavior. The charge storage characteristics of the device were found to be a combination of redox and electrostatic effects, forming a facile hybrid SC.

The transformation of recalcitrant pharmaceutical pollutants into products with diminished concerns via heterogeneous photocatalysis has gained considerable momentum over the past several years. However, practical applications of most semiconductor-based photocatalysts are severely restricted, attributed to insufficient visible light response pertaining to their wide band gap, ultrafast recombination of the photogenerated charge carriers, and issues corresponding to retrieval for persistent usage. Herein, rosette-like molybdenum disulfide (MoS2) nanoflowers are directly grown on the interpenetrating networks of graphene aerogels (GAs) through a facile one-step hydrothermal method, and the resulting lightweight, self-supporting composites are systematically assessed for the photocatalytic degradation of tetracycline (TC). Notably, after 120 min of exposure to visible light, ∼91% of TC is degraded over the MoS2/GAs, which is severalfold higher than pristine MoS2, standalone GA, and other contemporary photocatalysts. Based on the radical quenching assay, hydroxyl radicals and superoxide anions are the principal mediators of the photocatalytic dissociation of TC. Furthermore, the primary intermediates and residual products of the photocatalytic breakdown of TC are distinguished, and a conceivable disintegration pathway is proposed. Besides, these tailor-made hybrid aerogels can be recuperated easily and successfully reused over multiple cycles, suggesting their widespread consideration in photocatalytic wastewater treatment.

An innovative approach based on photothermal contrast to enhance analytical sensitivity of enzymatic phenylalanine detection at a solid surface was demonstrated. Gold nanoparticles in situ produced by the reduced form of nicotinamide adenine dinucleotide, which is generated by an enzymatic reaction, exhibit an excellent photothermal effect upon green-light stimuli. The enzymatic reaction and the nanoparticles process formation were optically investigated. A sensing range of 10–1000 μM with a detection limit of 3.6 μM for phenylalanine detection were demonstrated. The testing with blood samples collected from phenylketonuria patients together with concurrent comparison through tandem mass spectrometry have confirmed the good analytical performances and the robustness and utility of the proposed photothermal-contrast approach for further integration on clinical devices.

Photodynamic therapy (PDT) is a promising approach to cancer treatment, but the heterogeneity of the tumor microenvironment (TME) limits its application. Tumor vasculature is thought to be involved in abnormal TME. Therefore, tumor vascular normalization (TVN) is expected to be a strategy to reshape TME. We prepared a graded-release nanodrug combining TVN and PDT, named as PEVM, with the core of lipid nanoparticles for sustained release of anti-angiogenic drugs and the shell of a pH-sensitive polymer linked to a photosensitizer, and evaluated its therapeutic effect on a breast cancer model. We found that PEVM could achieve mutual benefits in both therapeutic effects. TVN not only increased the intratumoral oxygen level as a raw material for PDT, but also activated the anti-tumor immune response, further improving the efficacy of PDT. PEVM showed favorable anti-tumor efficiency and exhibited the potential of combining TVN and PDT.

Developing materials with outstanding performance for sorption thermal energy storage (STES) is vital in utilizing renewable energy. Metal–organic frameworks (MOFs) and covalent organic frameworks (COFs) have attracted much interest for application in STES due to their excellent adsorption properties, including large capacities and stepwise adsorption isotherms. However, the energy density (Qed), an essential property to look at when choosing a suitable material for STES, is still elusive due to the different composition methods in the experiment. This work evaluated and compared the material-based Qed’s of MOFs and COFs for STES via grand canonical Monte Carlo simulations. It was demonstrated that most MOFs exhibited larger Qed than COFs since MOFs tend to have high loading during the charging process. Nevertheless, it was found that one COF exhibited the highest Qed ascribed to the low density and complete desorption during the discharging process, which suggested that COFs can possess excellent performance as long as they achieve sufficient capacity during the charging process. Moreover, the structure–property relationship indicated that large pore volume, relatively small density, suitable carbon atom ratio, and isotropic 3D cage were favorable for large-Qed structures. The successful implementation of data mining and machine learning algorithms paves the way for rational design and speeds up the assessment of the Qed of nanoporous materials.

Constructing heterostructure in nanomaterials is a scientific and efficient method to optimize the electrochemical properties of supercapacitors. Carbon aerogels (CAs) can enhance electrical conductivity and ion diffusion because of their three-dimensional porous structure, which is useful for fabricating electrodes. The moderate nanoheterostructures in aerogel nanomaterials have made great contributions to the optimization of application performance. Herein, a simple method for constructing the MnO2 nanoparticle/CA (MnO2/CA) heterostructure is proposed. The MnO2/CA heterostructure exhibits outstanding electrochemical capability in a three-electrode system, with a specific capacitance of 384 F/g, higher than 201 F/g of the CA, at a current density of 0.5 A/g. When MnO2/CA is used as a symmetric supercapacitor, it also exhibits a high energy density and power density, with the highest energy density of 33.78 Wh/kg. The prepared MnO2/CA shows improved performance for synergies in providing a high specific capacity and long cycle life.