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The Sn-doped MnOx(0.25)/CoSn3Al-LDO catalyst by hydrothermal and impregnation methods achieves 100% NO conversion at 120–330 °C.

Halide perovskite quantum dots (HP QDs) have been widely used in the field of photocatalysis due to their excellent performance. However, the issues of lead toxicity and instability prevent their process in the photocatalysis application. Herein, the lead-free Cs2AgInCl6 perovskite quantum dots (CAIC QDs) are synthesized by the hot-injection method, and CAIC QDs@Ag composites with various Ag loading amounts are self-assembled by adjusting the Cl source in the synthesis process, which is used to improve the CO2 photoreduction efficiency by using the surface plasmon resonance (SPR) effect of Ag nanoparticles. In addition, the surface ligand density of CAIC QDs@Ag composites is regulated by the purification processing treatment to release the influence of organic ligands on the charge transport performance. It is found that the CAIC QDs@Ag composite with the optimal ligands density possesses fast electron transport and effective carrier separation efficiency, which are crucial for the improvement of the photocatalysis reaction. As a result, the CAIC QDs@Ag-2 composite after purification processing achieves the highest yield of 26.4 μmol g−1 and 28.9 μmol g−1 for CO and CH4, respectively, during the CO2 photoreduction process. In addition, there is no significant decline of CO2 photoreduction performance after the photocatalysis cycling test for 9 h, indicating the good stability of the CAIC QDs@Ag composite in the photocatalysis process.

The previous decades have witnessed increasing prevalence of research on chemiresistive gas sensors due to their high response, simple configuration and low cost. Chemiresistive gas sensors based on low-dimensional (0D, 1D and 2D) nanomaterials are remarkable because their high specific areas, abundant active sites and quantum effects in a certain dimension endow them with extraordinary gas sensing performance. Additionally, it has been gradually demonstrated that fabricating nanocomposites from various low-dimensional nanomaterials can further improve their sensing performance. The nanocomposites are generally in the form of 0D nanostructure-functionalized 1D or 2D nanomaterials. This review aims to elaborate the functionalization of 0D nanomaterials, including metal oxide semiconductors (MOSs), noble metals (NMs), metal chalcogenides (MCs), metal organics, conductive polymers (CPs) and others, on various 1D or 2D backbone nanomaterials. The content includes methods for depositing 0D nanomaterials on 1D or 2D backbones as well as the gas sensing performance and underlying mechanisms of 0D–1D and 0D–2D nanocomposites.

With the rapid development of perovskite solar cells (PSCs), it is critical to explore efficient and low-cost inorganic hole transport materials (HTMs) to solve the instability issue of the traditional organic HTM spiro-OMeTAD. Herein, Cu12Sb4S13 quantum dots (QDs) are applied as inorganic HTMs in n–i–p planar PSCs, the bandgap aligned the QDs is achieved by the modulation of the QD size to accelerate hole transport from the perovskite layer to QDs, and a power conversion efficiency (PCE) of 14.13% is achieved for 5.7 nm sized QDs. IPCE and UV-vis spectra indicate that the light absorption intensity of Cu12Sb4S13 QD based PSCs is slightly higher than that of the spiro-OMeTAD based one, which enables the enhancement of JSC (21.85 mA cm−2) for PSCs. The excellent hole transport behavior of Cu12Sb4S13 QDs proves that Cu12Sb4S13 QDs may be considered as an efficient and potential candidate of HTMs in PSCs. Moreover, the stability of the Cu12Sb4S13 QD based PSCs is significantly improved compared with that of the spiro-OMeTAD based one due to the high stability of Cu12Sb4S13 QDs and 91% of the initial PCE is retained after 30 days in ambient air.

Black phosphorus (BP) has gained great attention as a potential candidate in the photocatalytic field due to its tunable bandgap and high-mobility features, however, poor stability behavior and the high charge recombination of BP limit its practical application. In the present work, a liquid phase exfoliation method is employed to prepare layered BP. The as-prepared layered BP is decorated on TiO2 nanosheets to form a TiO2 nanosheets@BP composite, which stabilizes BP existence under a hydro-oxygen environment. Whereafter, the photocatalytic properties of the TiO2 nanosheets@BP composite towards the degradation of Rhodamine B (RhB) are proven to be greatly enhanced compared to those of pure layered BP and TiO2 nanosheets, and the photodegradation rate reached 98% after 120 minutes irradiation under UV-Vis light. It is worth mentioning that the photocatalytic cycling performance of the TiO2 nanosheets@BP composite remained at 92.5% under the irradiation of UV-Vis light after three cycles. The main reason for this lies in the fact that the formation of the TiO2 nanosheets@BP composite may favor light absorption and effectively reduce the recombination of electron–hole pairs.

The growing demands for reproducible and clean sources of power has prompted the exploitation of novel materials for solar-energy conversion; in any case, the improvement of their conversion efficiency remains a big challenge. We report a mixed-dimensional heterostructure to synchronously enhance charge separation and light-absorption of the photoanodes via the introduction of two-dimensional reduced graphene oxide and zero-dimensional CuSbS2 quantum dots on one-dimensional TiO2 arrays. The experimental results show that the graphene sheets with a low Fermi level and a superior electron mobility accept photo-excited electrons from TiO2 and enable fast electron transportation; while the CuSbS2 quantum dots promote the visible light-absorption of the photoanode. The synergistic effects in this mixed-dimensional (1D–2D–0D) heterostructure photoanode induce a markedly raised photoconversion efficiency of 1.2% at 0.3 V and a photocurrent density of 5.5 mA cm−2 at 0.4 V. Furthermore, the photocurrent density of the mixed-dimensional heterostructure exceeds previously reported TiO2-based photoanodes in neutral media. The improved photoelectrochemical properties are attributed to the synergistic-effect-induced highly organized, mixed-dimensional architectures. It is expected that the mixed-dimensional heterostructure photoanode will be a potential candidate for applications in environmental remediation and energy fields.

Here we address the optoelectronics properties of CuInSe2 and Mn doped CdS quantum dot (CISe/Mn-CdS QD) passivated layer solar cells. CISe/Mn-CdS QD solar cells exhibit a remarkably enhanced optical absorption in the visible region as well as monochromatic incident photon-to-electron conversion efficiency (IPCE) (up to 40–90%), which present the interesting photovoltaic efficiency of 3.96% under one sun illumination. Such remarkable optical behavior of the CISe/Mn-CdS QD passivated solar cells is explained by an optical mechanism based on an energy band model and valid physical laws.

Heterostructured V2O5/In2O3 core–shell nanorods were prepared by the combination of solid solution and hydrothermal methods. Microstructural and spectroscopic studies reveal the effective core–shell hetero-nanostructure. The gas sensor based on these nanorods exhibits remarkable gas sensing properties in both static and dynamic modes. It presents an optimum working temperature of 190 °C, a reasonable response speed and high selectivity with an ultra-stable reproducible response for n-propylamine. The sensor also shows enhanced optimum sensitivity (∼14), which is 3.90 times that of the pure V2O5 nanorods. Such promising gas sensing behavior of the hetero-nanostructured core–shell nanorods is explained using an energy band model and a suitable gas sensing mechanism has been established as well.

V2O5 nanoneedles were synthesized using a facile physical vapour deposition approach. The XRD patterns confirmed the good crystallinity of the as prepared nanoneedles. The chemical states of the V2O5 nanoneedles were confirmed through XPS analysis. Gas sensor based on the V2O5 nanoneedles was investigated for four types of gases (acetone, ammonia, ethanol and propylamine) at room temperature. A high reproducible response and a good selective behavior towards acetone were observed in both low and high concentration zones with a low detection limit of 941 ppb, which was explained on the basis of the energy band model. A sensing mechanism has also been suggested.

V2O5 nanowires decorated with SnO2 nanoparticles are prepared by two-step mild hydrothermal reaction, and the gas sensor device is fabricated by coating the nanowires as a thick film on the alumina tube. The pure V2O5 nanowires have almost no response to ethanol at room temperature, however, the sensitivity of V2O5 nanowires decorated with SnO2 nanoparticles is 1.46 upon exposure to 1000 ppm ethanol gas. The highest sensitivity of gas sensor based on V2O5 nanowires decorated with SnO2 nanoparticles to 1000 ppm ethanol is about 14, which is 2–3 times of pure V2O5 nanowires. The improved sensing performance of the composite is due to the increased depletion width and active sites along the nanowires, the energy gap between V2O5 nanowires and SnO2 nanoparticles promotes the electrons transport. Moreover, the gas sensor based on V2O5 nanowires decorated with SnO2 nanoparticles possesses a good selectivity to ethanol compared with other gases, such as CO2, H2O and NH3, and the stability of gas sensing performance is quite good, which implies that it would be a good candidate in the potential application.

Reduced graphene oxide (RGO)/P25 composites are successfully synthesized by using a facile hydrothermal method, and Raman mapping images show that the P25 are very uniformly dispersed in the composite. The RGO/P25 composites are used in the photocatalysis of methyl orange under UV and visible light illumination. The degradation ratio for the 0.75 wt% RGO/P25 composite is the best with 100% degradation after 120 and 150 minutes of irradiation under UV and visible light, respectively, which is greatly enhanced compared with that of P25, especially in the visible light region. It is found that a good interface combination between RGO and P25 may improve the electric conductivity and lifetime of photo-induced electrons in the photodegradation process as well as enhance the light absorption, which may favor the efficient enhancement of the photodegradation rate of the RGO/P25 composite.

TiO2 nanotube arrays have been widely used as the photoelectrode in dye-sensitized solar cells (DSSCs). In this work, free-standing TiO2 nanotube arrays were prepared by two-step electrochemical anodization of titanium foils, then the TiO2 nanotube arrays were transferred to a flexible ITO/PEN substrate using titania slurries. SEM images showed that the TiO2 nanotube arrays with different lengths (10, 14, 20 and 30 μm) were successfully obtained. The photovoltaic properties for incident photon to current efficiency (IPCE) and photovoltaic conversion efficiency were also studied, showing that the best photovoltaic conversion efficiency of DSSCs based on 20 μm length TiO2 nanotube arrays was 3.44%.

In the present work, we introduce a facile and widely used route to fabricate Cu2O nanocrystal/titanate nanobelt heterojunctions with high yield, good dispersion and tight interaction, and which are self-assembled via the linker molecule 3-mercaptopropionic acid. Their photocatalytic activity for the degradation of methyl orange solution is enhanced by decorating with Cu2O nanocrystals, especially in the visible light region. The degradation rates of 6 wt% Cu2O/titanate heterojunctions are both the highest at 100% after 80 and 180 minutes irradiation under UV and visible light irradiation, while those of the pure titanate nanobelts are only 20% and 3%, respectively. These lower values for the pure titanate nanobelts are due to the p–n heterojunctions suppressing the recombination of electron–hole pairs in the titanate nanobelts, where the Cu2O nanocrystals act as electron traps aiding electron–hole separation. Additionally, a synergistic effect from the tight contact between Cu2O nanocrystals and titanate nanobelts also efficiently enhances the photodegradation of the Cu2O/titanate heterojunctions.

In the present work, novel layered-structure titanate (H2Ti5O11·3H2O) nanobelts are synthesized by a hydrothermal method and then Pt nanocrystals/titanate nanobelts heterojunctions with high yield, well dispersion and tight interaction are self-assembled via the linker molecule of thioglycolic acid. Their photocatalytic activity for the degradation of methyl orange solution is enhanced by increasing the Pt precursor's content ratio. The degradation ratio of the heterojunctions with 11.0 wt% Pt nanocrystals will increase to 100% and 68.2% from 62% and 5% for pure titanate nanobelts after 300 min irradiation under UV and visible light irradiation, respectively. These are better when compared with similar reports, as the heterojunctions will suppress the recombination of electron-hole pairs in titanate nanobelts, where the Pt particles act as electron traps aiding electron-hole separation.