Infrared Black Phosphorus Phototransistor with Tunable Responsivity and Low Noise Equivalent Power

The narrow band gap property of black phosphorus (BP) that bridges the energy gap between graphene and transition metal dichalcogenides holds great promise for enabling broadband optical detection from ultraviolet to infrared wavelengths. Despite its rich potential as an intriguing building block for optoelectronic applications, however, very little progress has been made in realizing BP-based infrared photodetectors. Here, we demonstrate a high sensitivity BP phototransistor that operates at a short-wavelength infrared (SWIR) of 2 μm under room temperature. Excellent tunability of responsivity and photoconductive gain are acquired by utilizing the electrostatic gating effect, which controls the dominant photocurrent generation mechanism via adjusting the band alignment in the phototransistor. Under a nanowatt-level illumination, a peak responsivity of 8.5 A/W and a low noise equivalent power (NEP) of less than 1 pW/Hz^1/2 are achieved at a small operating source–drain bias of −1 V. Our phototransistor demonstrates a simple and effective approach to continuously tune the detection capability of BP photodetectors, paving the way to exploit BP to numerous low-light-level detection applications such as biomolecular sensing, meteorological data collection, and thermal imaging

Well-Dispersed Ruthenium in Mesoporous Crystal TiO₂ as an Advanced Electrocatalyst for Hydrogen Evolution Reaction

TiO₂ mesoporous crystal has been prepared by one-step corroding process via an oriented attachment (OA) mechanism with SrTiO₃ as precursor. High resolution transmission electron microscopy (HRTEM) and nitrogen adsorption–desorption isotherms confirm its mesoporous crystal structure. Well-dispersed ruthenium (Ru) in the mesoporous nanocrystal TiO₂ can be attained by the same process using Ru-doped precursor SrTi_1–<i>x</i>Ru_<i>x</i>O₃. Ru is doped into lattice of TiO₂, which is identified by HRTEM and super energy dispersive spectrometer (super-EDS) elemental mapping. X-ray photoelectron spectroscopy (XPS) and electron paramagnetic resonance spectroscopy (EPR) suggest the pentavalent Ru but not tetravalent, while partial Ti in TiO₂ accept an electron from Ru and become Ti³⁺, which is observed for the first time. This Ru-doped TiO₂ performs high activity for electrocatalytic hydrogen evolution reaction (HER) in alkaline solution. First-principles calculations simulate the HER process and prove TiO₂:Ru with Ru⁵⁺ and Ti³⁺ holds high HER activity with appropriate hydrogen-adsorption Gibbs free energies (Δ<i>G</i>_H)

A New Bis(phthalocyaninato) Terbium Single-Ion Magnet with an Overall Excellent Magnetic Performance

Bulky and strong electron-donating dibutylamino groups were incorporated onto the peripheral positions of one of the two phthalocyanine ligands in the bis­(phthalocyaninato) terbium complex, resulting in the isolation of heteroleptic double-decker (Pc)­Tb­{Pc­[N­(C₄H₉)₂]₈} {Pc = phthalocyaninate; Pc­[N­(C₄H₉)₂]₈ = 2,3,9,10,16,17,23,24-octakis­(dibutylamino)­phthalocyaninate} with the nature of an unsymmetrical molecular structure, a square-antiprismatic coordination geometry, an intensified coordination field strength, and the presence of organic radical-f interaction. As a total result of all these factors, this sandwich-type tetrapyrrole lanthanide single-ion magnet (SIM) exhibits an overall enhanced magnetic performance including a high blocking temperature (<i>T</i>_B) of 30 K and large effective spin-reversal energy barrier of <i>U</i>_eff = 939 K, rendering it the best sandwich-type tetrapyrrole lanthanide SIM reported thus far