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Perovskites have showed significant potential for the application in photodetectors due to their outstanding electrical and optical properties. Integrating two-dimensional (2D) materials with perovskites can make full use of the high carrier mobility of 2D materials and strong light absorption of perovskite to realize excellent optoelectrical properties. Here, we demonstrate a photodetector based on the WTe2/CsPbI3 heterostructure. The quenching and the shortened lifetime of photoluminescence (PL) for CsPbI3 perovskite confirms the efficient charge transfer at the WTe2/CsPbI3 heterojunction. After coupled with WTe2, the photoresponsivity of the CsPbI3 photodetector is improved by almost two orders of magnitude due to the high-gain photogating effect. The WTe2/CsPbI3 heterojunction photodetector reveals a large responsivity of 1157 A W−1 and a high detectivity of 2.1 × 1013 Jones. The results pave the way for the development of high-performance optoelectronic devices based on 2D materials/perovskite heterojunctions. [ABSTRACT FROM AUTHOR]

The potential‐driven semiconductor‐to‐metal transition is investigated in monolayer transition metal dichalcogenides by employing a new proposed method, i.e., the fixed‐potential method (FPM). Under the same voltage, the semiconducting and metallic phases will be charged differently due to their different electronic properties. The potential‐driven phase transition process is simulated by the injection of unequal electrons in the semiconducting and metallic phases. The unequal electron injection is more consistent with the actual experimental process, although equal electron injection also can theoretically induce a phase transition. MoTe2 is chosen as a prototypical example to examine the physical mechanism. When the fixed electrode potential is above the potential of zero‐charge, excess electrons are injected into the metallic 1T' phase instead of the semiconducting 2H phase, stabilizing the 1T' phase. In addition, the potential‐dependent kinetics, in which the charge transfer is fluctuating, suggests that increasing the electrode potential will decrease the kinetic barrier of the 2H→1T' transition process. The calculated relative transition voltage of 2.5 V agrees well with the experimental results, demonstrating the validity of the FPM. This study provides new insight into potential‐driven semiconductor‐to‐metal phase transitions and suggests a new theoretical approach for studies under constant voltage conditions. [ABSTRACT FROM AUTHOR]

In recent years, heteroatom-doped carbon nanomaterials without metal possess great potential in oxygen evolution reactions (OER). However, the synthesis process is complex and the energy waste is large (i.e. calcination). Molecular electrocatalysts, as a new type of electrocatalyst for oxygen evolution, have attracted a wide amount of attention. In this work, taurine (TA) was selected as an OER electrocatalyst, and the catalytic activity of TA was studied via theoretical calculations and experiment. The DFT results show that the OH in the electrolyte tends to adsorb on C or N and takes away the H atom on the amino group to form uncoordinated N atoms in TA molecules. In addition, the TA molecule is fixed in a conductive hydrogel with a hydrophilic surface, and the conductive network on the hydrogel further accelerates charge and mass transfer in the OER process. Therefore, this work opens the way for further research on molecular electrocatalysts. [Display omitted] • the TA molecules provided positively charged atoms with high activity towards the OER demonstrated by DFT calculations. • the conductive PPy networks allowed fast charge transfer during the OER. • The TA-PPy hydrogel was directly grown on the carbon cloth without the usage of binders. [ABSTRACT FROM AUTHOR]

[Display omitted] • CAS-CdS-ZnO photocatalysts were synthesized by simple rapid microwave irradiation synthesis. • The photocatalytic activity of CAS-CdS-ZnO photocatalyst was investigated. • The effects of adjusting band alignment to photocatalyst were in-depth discussion with characterization and DFT calculation. • A method of adjusting band alignment to reduce interfacial recombination and improve photocatalytic performance was proposed. Photocatalytic technology based on heterojunction structure has been proved to be an effective way to solve environmental pollution and energy crisis. The effective carrier concentration plays an important role in improving the performance of heterojunction photocatalyst. In this work, CuSbS 2 (CAS)-CdS-ZnO was prepared by simple 3-steps microwave irradiation method to reveal the influence of energy band structure on photocatalytic performance. Adding CdS could regulate band alignment to translate the "cliff-like" conduction band offset of CAS-ZnO to "spike-like". That could effectively reduce the carrier recombination rate to improve the photocatalytic degradation activity, which could completely degraded Rhodamine B (RhB) after 80 min under a solar simulation, highest rate constant (0.02028 min−1) and good stability. Furthermore, the transformation of charge transfer mechanism from the Z-type to Ⅱ-type by adding CdS were confirmed by experiments and density functional theory (DFT) calculations. This change could raise the energy level of photoelectrons, resulting in CAS-CdS-ZnO with a certain photocatalytic hydrogen evolution capacity (42.37 μmol g−1 h−1). This work reveals the important role of band structure in photocatalytic properties and applications of heterojunction. [ABSTRACT FROM AUTHOR]