In this work, in order to enhance the performance of graphene gas sensors, graphene and metal oxide nanoparticles (NPs) are combined to be utilized for high selectivity and fast response gas detection. Whether at the relatively optimal temperature or even room temperature, our gas sensors based on graphene transistors, decorated with SnO2 NPs, exhibit fast response and short recovery times (∼1 seconds) at 50 °C when the hydrogen concentration is 100 ppm. Specifically, X-ray photoelectron spectroscopy and conductive atomic force microscopy are employed to explore the interface properties between graphene and SnO2 NPs. Through the complimentary characterization, a mechanism based on charge transfer and band alignment is elucidated to explain the physical originality of these graphene gas sensors: high carrier mobility of graphene and small energy barrier between graphene and SnO2 NPs have ensured a fast response and a high sensitivity and selectivity of the devices. Generally, these gas sensors will facilitate the rapid development of next-generation hydrogen gas detection.

This work shows a novel artificial Z‐scheme photosystem based on a heterometallic Zn‐/Pt‐porphyrin conjugated polymer (ZnPtP‐CP) grafted onto ultrathin BiVO4 nanosheets via Zn–O–V bridging bonds for high‐efficiency overall water photosplitting. An impressive apparent quantum yield of 9.85% at λ = 400 nm is achieved over the resulting ZnPtP–CP/BiVO4 composite, in which BiVO4 nanosheets are in close contact with ZnPtP‐CP nanosheets via Zn–O–V bridging bonds to promote a Z‐scheme charge transfer mechanism with ZnPtP‐CP serving as electron‐rich unit and BiVO4 as hole‐rich one. The photoexcited electrons of BiVO4 transfer to the interface and recombine with the photogenerated holes of ZnPtP‐CP through the Zn–O–V bonds, and thus the strong reducibility of the photoinduced electrons in ZnPtP‐CP and the strong oxidation ability of the photogenerated holes in BiVO4 are maintained. Moreover, the highly dispersed Pt centers (PtN4) in Pt‐porphyrin bridging units act as single‐atom catalytic sites to facilitate a cascade charge transfer by fast migration of the photogenerated electrons from Zn‐porphyrin to Pt‐porphyrin units for the water reduction reaction. This Z‐scheme mechanism with two‐step excitation and cascade charge transfer pathway makes the composite acting as Z‐scheme dual‐function photocatalyst responsible for the efficient solar‐driven overall water photosplitting without the aid of a sacrificial reagent or external bias.

This study examined the electrical performance of bilayer channel InGaZnO:H/InGaZnO thin-film transistors (TFTs). The field-effect mobility and bias stress stability of the InGaZnO device were improved by inserting the hydrogenated InGaZnO ultrathin layer compared to the pure InGaZnO single channel layer device. As a consequence, a high field-effect mobility of 55.3 cm2/V s, a high on/off current ratio of 108, a threshold voltage of 0.7 V, and a small sub-threshold swing of 0.18 V/decade have been achieved. The X-ray photoelectron spectroscopy and low-frequency noise analysis suggest that these desirable properties should be attributed to the ultrathin InGaZnO:H layer, which could provide suitable carrier concentration and reduce the average trap density near the channel and insulator layer interface. Meanwhile, the channel conductance of the bilayer device is controlled by thick InGaZnO layer through formation barrier energy for electron transport at the interface of InGaZnO:H and InGaZnO layer. These improved electrical properties have represented a great step towards the achievement of transparent, high performances, and low-cost metal oxide TFTs.

A novel heterometallic Zn‐/Co‐porphyrin conjugated polymer (ZnCoP‐F CP) with its Co‐porphyrin bridging unit bearing two perfluorophenyls is synthesized via a Sonogashira coupling reaction. The resulting ZnCoP‐F CP without the Pt cocatalyst exhibits broadband (UV–vis–NIR) light‐driven hydrogen evolution activity of 83 µmol h−1, which is more than twice that (39 µmol h−1) of its counterpart (ZnCoP CP) with the Co‐porphyrin unit bearing two phenyls. Furthermore, an apparent quantum yield of 6.92%, 5.50%, 5.78%, 3.17%, and 0.73% is achieved from the ZnCoP‐F CP illuminated at 400, 500, 550, 700, and 850 nm monochromatic light, respectively. The enhanced performance of ZnCoP‐F CP can be attributed to the high electron‐withdrawing capacity of its perfluorophenyls and the highly dispersed Co centers in Co‐porphyrin bridging units serving as single‐atom catalytic sites (CoN4), which facilitate the formation of periodic type II‐like heterojunctions and the fast charge transfer from Zn‐porphyrin to Co‐porphyrin units for hydrogen evolution reaction. The broadband‐responsive feature is due to the large π‐conjugated system through the whole 2D internal framework of the porphyrin polymer. This work opens a new path to fabricate porphyrin‐based polymer with an efficient and broadband‐responsive hydrogen evolution system.

Despite intensive research on improvement in electrical performances of ZnO-based thin-film transistors (TFTs), the instability issues have limited their applications for complementary electronics. Herein, we have investigated the effect of nitrogen and hydrogen (N/H) codoping on the electrical performance and reliability of amorphous InGaZnO (α-IGZO) TFTs. The performance and bias stress stability of α-IGZO device were simultaneously improved by N/H plasma treatment with a high field-effect mobility of 45.3 cm/(V s) and small shifts of threshold voltage (V). On the basis of X-ray photoelectron spectroscopy analysis, the improved electrical performances of α-IGZO TFT should be attributed to the appropriate amount of N/H codoping, which could not only control the V and carrier concentration efficiently, but also passivate the defects such as oxygen vacancy due to the formation of stable Zn-N and N-H bonds. Meanwhile, low-frequency noise analysis indicates that the average trap density near the α-IGZO/SiO interface is reduced by the nitrogen and hydrogen plasma treatment. This method could provide a step toward the development of α-IGZO TFTs for potential applications in next-generation high-definition optoelectronic displays.

The intriguing properties of zinc oxide-based semiconductors are being extensively studied as they are attractive alternatives to current silicon-based semiconductors for applications in transparent and flexible electronics. Although they have promising properties, significant improvements on performance and electrical reliability of ZnO-based thin film transistors (TFTs) should be achieved before they can be applied widely in practical applications. This work demonstrates a rational and elegant design of TFT, composed of poly crystalline ZnO:H/ZnO bilayer structure without using other metal elements for doping. The field-effect mobility and gate bias stability of the bilayer structured devices have been improved. In this device structure, the hydrogenated ultrathin ZnO:H active layer (∼3 nm) could provide suitable carrier concentration and decrease the interface trap density, while thick pure-ZnO layer could control channel conductance. Based on this novel structure, a high field-effect mobility of 42.6 cm(2) V(-1) s(-1), a high on/off current ratio of 10(8) and a small subthreshold swing of 0.13 V dec(-1) have been achieved. Additionally, the bias stress stability of the bilayer structured devices is enhanced compared to the simple single channel layer ZnO device. These results suggest that the bilayer ZnO:H/ZnO TFTs have a great potential for low-cost thin-film electronics.

The early stages of formation of intermetallic compounds (IMC) have been investigated in dissimilar aluminum to steel welds, manufactured by high power (2.5 kW) ultrasonic spot welding (USW). To better understand the influence of alloy composition, welds were produced between a low-carbon steel (DC04) and two different aluminum alloys (6111 and 7055). The joint strengths were measured in lap shear tests and the formation and growth behavior of IMCs at the weld interface characterized by electron microscopy, for welding times from 0.2 to 2.4 seconds. With the material combinations studied, the η (Fe 2 Al 5 ) intermetallic phase was found to form first, very rapidly in the initial stage of welding, with a discontinuous island morphology. Continuous layers of η and then θ (FeAl 3 ) phase were subsequently seen to develop on extending the welding time to greater than 0.7 seconds. The IMC layer formed in the DC04-AA7055 combination grew thicker than for the DC04-AA6111 welds, despite both weld sets having near identical thermal histories. Zinc was also found to be dissolved in the IMC phases when welding with the AA7055 alloy. After post-weld ageing of the aluminum alloy, fracture in the lap shear tests always occurred along the joint interface; however, the DC04-AA6111 welds had higher fracture energy than the DC04-AA7055 combination.

Novel hollow ZnO microstructures and ZnO microberets (ZMBs) with nanowires grown vertically on both the inner and outer surfaces of beret shells were synthesized on Si(100) substrates by simple thermal evaporation of pure zinc powder without any catalyst or template material at a relative low temperature of 490 degrees C. XRD, SAED, and HRTEM patterns show that the nanowires and shells of ZMBs are single-crystalline wurtzite structures. The growth mechanism of ZMBs is discussed in detail. The formation of these hollow microstructures depends on the optimum starting time of air introduction. It is a good way to grow well-aligned nanowires by using a nanoscale rough ZnO surface to realize a "self-catalyzed" vapor-liquid-solid process. The photoluminescence spectrum reveals a strong green emission related to the high surface-to-volume ratio of ZMBs. These types of special hollow high surface area structural ZMBs may find potential applications in functional architectural composite materials, solar cell photoanodes, and nanooptoelectronic devices.