The two-terminal memristor, characterized by their low power consumption, tunable resistance, simple structure, and compatibility with CMOS processes, have found applications in memory storage, logic circuits, and synaptic functions of the simulated human brain. Graphene oxide quantum dots (GO-QDs), a zero-dimensional nanocarbon material, are noted for their low cost and eco-friendliness, making them suitable for electrocatalysis and the fabrication of various optoelectronic devices such as batteries, supercapacitors, and light-emitting diodes. In this paper, we report a two-terminal memristor based on GO-QDs doped with poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT-PSS). Through systematic optimization of our experimental protocol, we found that a doping concentration of 60 % resulted in optimal device performance, achieving an ON/OFF current ratio (Ion/off) up to 104 and retention capability lasting up to 104 s. Through the analysis of the optoelectronic properties of the films, fitting of the I-V characteristics, and electrochemical impedance spectroscopy (EIS) tests, we confirmed that the resistive switching mechanism is the trapping and detrapping process of charge traps induced by PEDOT-PSS or GO-QDs.

In this work, the adsorption behaviors of 10 gas molecules, namely CO, CO 2 , H 2 O, H 2 S, N 2 , N 2 O, NO, NO 2 , O 2 and SO 2 , on B doped monolayer MoS 2 were investigated by studying their adsorption configurations, charge density differences, density of state and recovery times. The results indicate that, except for CO 2 (which exhibits weak adsorption), all other molecules undergo chemical adsorption on B doped MoS 2 . Among them, B doped MoS 2 demonstrates the strongest binding affinity for NO and O 2 , with adsorption energies of −3.81 eV and −2.77 eV, respectively. After adsorption, CO 2 , H 2 O and H 2 S act as electron donors, while the other 7 molecules are electron acceptors. Interestingly, the recovery time for CO 2 at room temperature is very short (1.6 × 10 –8 s). Therefore, B doped MoS 2 can serve as a detector for CO 2 among these gas molecules and as a scavenger for removing the remaining 9. This work provides important guidance for designing MoS 2 -based gas detectors and scavengers.

By using density functional theory (DFT), the adsorption behavior of gas molecules on defective graphene doped with manganese and nitrogen were investigated. The geometric structure, electronic structure, and magnetic properties of two substrates were calculated and the sensing mechanism was also analyzed. The results indicate that the MnSV-GP and MnN3-GP have stronger structural stability, in which Mn atoms and their coordination atoms will become the adsorption point for five gas molecules (CH2O, CO, N2O, SO2, and NH3), respectively. Moreover, at room temperature (298 K), the recovery time of the MnSV-GP sensor for N2O gas molecules is approximately 1.1 s. Therefore, it can be concluded that the MnSV-GP matrix as a magnetic gas sensor has a promising potential for detecting N2O. These results also provide a new pathway for the potential application of Mn-doped graphene in the field of gas sensors.

Herein, we have investigated the adsorption behavior of gas molecules, including C2H2, H2S, SO2, SO3, and O2, on FeN3-doped graphene (FeN3-gra). The change of geometric stability, electric structure, and magnetic properties is discussed comprehensively. The results have demonstrated that the stability of the substrate is enhanced by the hybridization between Fe and N atoms in FeN3-gra. Besides, the Fe dopant can enhance the adsorption ability of gases on graphene. The gas molecules all exhibit high binding strength on FeN3-gra especially for SO3 with the adsorption energy of -3.30 eV. The mechanism of interaction between gases and substrate is investigated based on the charge density difference and density of states, which can clarify the distribution of electrons and magnetic moments. Moreover, the high stability and sensitivity of FeN3-gra are promising characters for gas detection. Our research has paved the way for the application of the graphene-based material in gas sensor and electronic instrument.

Herein, the adsorption characteristics of graphene substrates modified through a combined single manganese atom with a vacancy or four nitrogen to CH2O, H2S and HCN, are thoroughly investigated via the density functional theory (DFT) method. The adsorption structural, electronic structures, magnetic properties and adsorption energies of the adsorption system have been completely analyzed. It is found that the adsorption activity of a single vacancy graphene-embedded Mn atom (MnSV-GN) is the largest in the three graphene supports. The adsorption energies have a good correlation with the integrated projected crystal overlap Hamilton population (-IpCOHP) and Fermi softness. The rising height of the Mn atom and Fermi softness could well describe the adsorption activity of the Mn-modified graphene catalyst. Moreover, the projected crystal overlap Hamilton population (-pCOHP) curves were studied and they can be used as the descriptors of the magnetic field. These results can provide guidance for the development and design of graphene-based single-atom catalysts, especially for the support effect.

Herein, we have used density functional theory (DFT) to investigate the adsorption behavior of gas molecules on Co/N3 co–doped graphene (Co/N3–gra). We have investigated the geometric stability, electric properties, and magnetic properties comprehensively upon the interaction between Co/N3–gra and gas molecules. The binding energy of Co is −5.13 eV, which is big enough for application in gas adsorption. For the adsorption of C2H4, CO, NO2, and SO2 on Co/N–gra, the molecules may act as donors or acceptors of electrons, which can lead to charge transfer (range from 0.38 to 0.7 e) and eventually change the conductivity of Co/N–gra. The CO adsorbed Co/N3–gra complex exhibits a semiconductor property and the NO2/SO2 adsorption can regulate the magnetic properties of Co/N3–gra. Moreover, the Co/N3–gra system can be applied as a gas sensor of CO and SO2 with high stability. Thus, we assume that our results can pave the way for the further study of gas sensor and spintronic devices.

In surface-enhanced Raman scattering (SERS), both chemical (CE) and electromagnetic (EM) field effects contribute to its overall enhancement. However, neither the quantification of their relative contributions nor the substrate dependence of the chemical effect have been well established. Moreover, there is to date no understanding of a possible coupling between both effects. Here we demonstrate how systematically engineered silver and gold planar and nanostructured substrates, covering a wide range of field enhancements, provide a way to determine relative contributions of chemical and electromagnetic field-enhancement in SERS measurements of benzenethiol. We find a chemical enhancement of 2 to 14 for different vibrational resonances when referencing against a vibrational mode that undergoes minimal CE. The values are independent of substrate type and independent of the enhancement of the electromagnetic intensity in the range from 1 to 106. This absence of correlation between chemical and electromagnetic enhancement resolves several long-standing controversies on substrate and intensity dependence of the chemical enhancement and allows for a more systematic design of SERS substrates with desired properties.

In this work, titanium dioxide thin films doped with different concentrations of gadolinium (Gd) and iodine (I) were synthesized using the sol–gel method and successfully coated on solid waste material (made in our lab) by dipping, resulting in the titanium dioxide thin-film-coated material (TiO2M). Then, the doped titanium dioxide thin films were characterized by X-ray diffraction (XRD), SEM, and UV–Vis spectroscopy; the optimum coating cycle was evaluated by removal rates of COD and ammonia nitrogen in raw wastewater and secondary effluent. Moreover, the photocatalytic activity was determined by degradation efficiency of methyl orange. The results showed that TiO2M had desirable reusability and the photocatalytic activity was attractive under ultraviolet light irradiation. Furthermore, it is found that the amount of dopant in TiO2 was a key parameter in increasing the photoactivity. 1% Gd-doped TiO2M exhibited the best photocatalytic activity for the degradation of methyl orange with the removal rate reaching 85.55%. The result was in good agreement with the observed smaller crystallite size and profitable crystal structure (anatase phase). Besides, the TiO2M (0.8% Gd-doped TiO2M, 1% Gd-doped TiO2M, 10% I-doped TiO2M, and 5% I–1% Gd-doped TiO2M) with desirable photocatalytic activity at ultraviolet light irradiation was selected for the visible light photocatalytic experiments with taking methyl orange as the target pollutants. The results showed that all of them exhibited the similar photocatalytic activity after 7 h of sunlight irradiation (around 90% removal effect). In general, this research developed a very effective and environmentally friendly photocatalyst for pollutant degradation.

Surface-enhanced Raman scattering (SERS) substrates with high density and uniformity of nanogaps are proven to enhance the reproducibility and sensitivity of the Raman signal. Up to now, the syntheses of a highly ordered gold or silver superstructure with a controllable nanoparticle size and a well-defined particle gap have been quite limited. Here, we reported an ordered mesoporous silver superstructure replicated by using ordered mesoporous KIT-6 and SAB-15 as templates. By means of a nanocasting process, the ordered mesoporous Ag superstructure was successfully synthesized, which shows uniform distribution of the nanowire diameter (10 nm) and nanogap size (∼2 nm), thus exhibiting a high Raman enhancement of ∼10(9). The finite difference time-domain (FDTD) results indicate that the ordered mesoporous Ag superstructure has a uniform distribution of hot spots. Therefore, the mesoporous silica template strategy presented here could lead to a new class of high quality SERS substrates providing extraordinary potential for diverse applications.