This paper reports a facile solvothermal method for the in situ growth of vertically aligned InS nanosheet arrays (NSAs) on fluorine-doped tin oxide substrates. The as-synthesized two-dimensional graphene-like InS nanosheets show an ultrathin thickness down to 3.7 nm consisting of the duodenary interplanar spacing of the (222) plane and a tunable bandgap varying from 2.32 to 2.58 eV. The film thickness and nanosheet density of the InS NSAs can be adjusted by varying the reaction time and precursor concentration. The InS NSAs with a higher film thickness exhibit relatively higher photocurrent due to their stronger light absorption as well as larger surface area for sufficient charge separation and redox reaction. The photoelectrochemical performance of the InS photoanodes can be greatly enhanced by constructing an effective heterojunction with ZnO to promote the photocarrier separation. The InS/ZnO NSAs have demonstrated an optimal photocurrent density of 349.1 μA cm at 1.2 V vs. RHE and a maximum incident photon to current efficiency of 10.26% at 380 nm, which are 13.5 and 38 times higher than those of the pristine InS counterparts, respectively.

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that of conventional narrow-bandgap semiconductors, which enable SWCNTs to be used in semitransparent or transparent photodetectors with thinner active materials. [7] In addition, it has been theoretically and experimentally demonstrated that multiple electron-hole pairs can be generated from one high-energy photon in S-SWCNTs, [8,9] which provides the possibility for fabricating high performance photoelectronic devices.Apart from the different device architectures, the SWCNT-based photodetectors have been extensively investigated using different nanotube types as a light absorber, such as individual SWCNT, aligned SWCNT arrays, SWCNT networks, and SWCNT films. [3,10,11] Compared with the former two types, the SWCNT film/networks favor the largescale fabrication of high-performance photodetectors with low-cost due to their simple process, high optical absorption, and good device reliability. To improve the performance of SWCNT-based photodetectors, low-dimensional carbon allotropes are widely used to form all-carbon heterojunctions with SWCNTs due to the intimate electronic coupling between the two sp 2 -hybridized carbon allotropes. [12] In addition, the devices with planar structures are adopted, in which the exciton diffusion along the SWCNTs plays a major role while the exciton diffusion perpendicular to the films is suppressed. Park et al. [13] demonstrated an SWCNT/C 60 -based phototransistor with the C 60 serving as electron traps and the SWCNTs as the hole carrier. The maximum responsivity and detectivity are 97.5 A W −1 at gate voltage of −2 V and 1.17 × 10 9 Jones at 1 kHz, respectively. Except for 0D C 60 , 2D graphene has also been demonstrated to enhance significantly the carrier separation by forming the Schottky junctions with S-SWCNTs due to exceedingly high carrier mobility and thermal conductivity. [14,15] Liu et al. [3,16] demonstrate an effective charge transfer between SWCNTs and graphene in the planar nanohybrids. Zhang et al. [17] developed the SWCNT film/graphene Schottky junctions for visible-NIR photodetector. The device exhibits a fast response time of 68 µs and good reproducibility in a wide range of 50-5400 Hz. However, it is still a big challenge to further improve the performance. First, the ultrathin S-SWCNT layer means poor optical absorption, which will be difficult to meet the different application requirements. While dark current will be increased with increasing the thickness or density of SWCNTs. On the other hand, continuous graphene sheets in the planar nanohybrids give a very large dark Single-walled carbon nanotube (SWCNT)/graphene Schottky junctions have great potential for high-performance all-carbon photodetector due to their excellent optical and electronic properties and efficient charge transfer. However, the further improvement of device performance is limited by the low absorption of ultrathin SWCNTs and large dark current of continuous graphene nanosheets. Here a proof-of-concept photodetector is reported using SWCNT/separated graphene (SGR) hybrid networks. The ...

Photoanodes based on In2S3/ZnO heterojunction nanosheet arrays (NSAs) have been fabricated by atomic layer deposition of ZnO over In2S3 NSAs, which were in situ grown on fluorine-doped tin oxide glasses via a facile solvothermal process. The as-prepared photoanodes show dramatically enhanced performance for photoelectrochemical (PEC) water splitting, compared to single semiconductor counterparts. The optical and PEC properties of In2S3/ZnO NSAs have been optimized by modulating the thickness of the ZnO overlayer. After pairing with ZnO, the NSAs exhibit a broadened absorption range and an increased light absorptance over a wide wavelength region of 250–850 nm. The optimized sample of In2S3/ZnO-50 NSAs shows a photocurrent density of 1.642 mA cm−2 (1.5 V vs. RHE) and an incident photon-to-current efficiency of 27.64% at 380 nm (1.23 V vs. RHE), which are 70 and 116 times higher than those of the pristine In2S3 NSAs, respectively. A detailed energy band edge analysis reveals the type-II band alignment of the In2S3/ZnO heterojunction, which enables efficient separation and collection of photogenerated carriers, especially with the assistance of positive bias potential, and then results in the significantly increased PEC activity.Electronic supplementary materialThe online version of this article (10.1007/s40820-018-0199-z) contains supplementary material, which is available to authorized users.

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