Low‐Temperature Growth of High‐Quality Ag₂HgS₂ Crystals for Setup of Weak‐Light UV–Visible–NIR Photodetectors

Abstract

their ternary alloys, typically including CdTe, [5] HgCdTe, [6,7] InAs, [8,9] InAsSb, and InGaAs, [10][11][12][13] were proved to be the most promising infrared materials, and most of them have already been utilized in various aspects for photodetections commercially. [14,15] Generally, the light power of the common infrared radiation is relatively low from the traditional infrared materials, which would be less effective in most cases for weak light detection in infrared regions. So, it is highly necessary to find out possible new candidates for photodetection of weak infrared light sensitively.Ag 2 HgS 2 exists naturally as a stable mineral known as imiterite with monoclinic phase, which was first discovered in Morocco in 1985. [16] However, it was only fabricated till 2002 via the initially successful solvothermal synthesis at 180−200 °C for long reaction time (5 days) while the samples were only picked up from the mixture with the corresponding endmembers of Ag 2 S and HgS. [17] Thereafter, Ag 2 HgS 2 powders with diameters of ≈200 nm were obtained via a similar process with some modifications of precursors along with their feedstocks [18] and they were also fabricated via a microwave-assisted solvothermal route, in which the reaction system was irradiated using 100 W microwave (2450 MHz) for 1 h. [19] Powder samples with granular sizes of ≈200 nm in diameter were not suitable for fabrication of optoelectronic devices conveniently due to the granular Weak-light photodetection shows considerable potential in both theoretical and technical aspects while it would be a key issue to explore new candidate materials for practical application in view of high reliability and durability of the devices under ambient conditions. In this work, Ag 2 HgS 2 single crystal rods (SCRs) with length up to 1.2 cm and width ranging from 10 to 200 µm are successfully fabricated in pure phase via facile solvothermal process at 200 °C for 24 h for the first time. The Ag 2 HgS 2 SCRs are technically investigated, and the study reveals that they are in high quality via the determination of their crystal structure, morphology, and optical properties. Density functional theory (DFT) calculations are carried out to explore more reliably details on the band structure of bulk Ag 2 HgS 2 . Meanwhile, a series of photodetectors based on the individual Ag 2 HgS 2 SCRs are fabricated, and they convey sensitive responses to a 0.170 µW cm −2 weak light and unanimous responses to incident light with different wavelengths from 254 to 980 nm. In addition, the devices show excellent detecting performances without any obvious slump after the Ag 2 HgS 2 SCRs exposed in air over 18 months.Recently, the exploration of new kinds of infrared light mate-

Few‐Layer Ag‐Coated Ordered Mesoporous Pt Nanocrystals for Ethanol Oxidation

“…In the close‐up XPS spectra for Ag MN1 of Meso‐Pt@Ag 2 (Figure 3d), there are two obvious Auger peaks at around 351.9 and 357.5 eV, which is well consistent with previous reports. [ 31 ] Combing the spectra for Ag 3d and Ag MN1, the composition of Ag can be confirmed as metallic Ag 0 in Meso‐Pt@Ag 2 . Moreover, by observing XPS spectra for Ag 3d of Meso‐Pt@Ag 1 , Meso‐Pt@Ag 2 , Meso‐Pt@Ag 3 , and Meso‐Pt@Ag 4 (Figure S8b, Supporting Information), it can be seen that the peak position shifts negatively with the increase of Ag content.…”