There has been a spurt of activity in using layered MPX 3 (M = transition metal, X = chalcogen, S/Se/Te) compounds in various studies including catalysis and devices.In the present study, low band gap, ternary iron selenophosphate (FePSe 3 ) is introduced as an excellent and highly stable trifunctional electrocatalyst for hydrogen evolution, oxygen evolution, and oxygen reduction reactions. It is observed that the present catalyst is useful in evolving hydrogen over a wide pH range including seawater environment. Density functional theory calculations reveal various parameters that help improve the electrocatalytic activity of the layered material. Covalency of the Fe−Se bond, distortion in the crystal structure, and adsorption properties are shown to be responsible for the observed high catalytic activity.

Two dimensional few-layer and bulk MnPS3-based field effect transistors and photodetectors.

Layered metal phosphochalcogenides of molecular formula, MPX3 (M = Mn, Fe, Co, Ni, etc and X = S, Se) have been emerging as new class of semiconductors towards various catalytic and optoelectronic applications. The low cleavage energy associated with these layered chalcogenides may lead to devices with very thin semiconductor channels. Herein, we report the first successful fabrication of field effect transistor (FET) using layered NiPS3 that reveals n-type semiconducting behavior. Devices using bulk and few-layer NiPS3 with gold contacts show on/off ratios of ~103–105 at 25 °C. The device characteristics reveal an increase in on-state current with decrease in threshold voltage and the Schottky barrier height is extracted to be 112 meV. Density functional theory calculations reveal various parameters that affect electron/hole doping in the layered phosphochalcogenide material.

A two‐dimensional, few‐layer nickel thiophosphate, NiPS3, was introduced as a hydrogen evolution reaction catalyst from aqueous acidic, alkaline, and neutral solutions. NiPS3 is semiconducting in nature, and its band structure calculations revealed the importance of the [P2S6]4− units in the adsorption of hydrogen and subsequent evolution. Onset potentials of −0.062, −0.065, and −0.298 V versus RHE were observed in acidic, alkaline, and neutral media. Tafel slopes of 55, 48, and 94 mV dec−1 and exchange current densities of 1.8×10−4, 6.1×10−4, and 3.2×10−5 A cm−2 were observed in aqueous 0.5 m H2SO4, 1 m KOH, and 3.5 % NaCl solutions, respectively. The catalyst was found to be very stable, and the constituting elements are earth abundant. The present study opens up a new class of semiconducting layered materials to catalyze various redox reactions. Achieving a single layer will be of great interest to electrical and magnetic devices.

Engineering the electronic structure of metal, N-doped carbon catalysts is a potential strategy for increasing the activity and selectivity of CO 2 electroreduction reaction (CO 2 RR). However, establishing a definitive link between structure and performance is extremely difficult due to constrained synthesis approaches that lack the ability to precisely control the specific local environment of MNC catalysts. Herein, a soft-template aided technique is developed for the first time to synthesize pyrrolic N 4 Ni sites coupled with varying N-type defects to synergistically enhance the CO 2 RR performance. The optimal catalyst helps attain a CO Faradaic efficiency of 94% at a low potential of −0.6 V and CO partial current density of 59.6 mA cm −2 at −1 V. Results of controlled experimental investigations indicate that the synergy between NiN 4 and metal free defect sites can effectively promote the CO 2 RR activity. Theoretical calculations revealed that the pyrrolic N coordinated NiN 4 sites and C atoms next to pyrrolic N (pyrrolic NC) have a lower energy barrier for the formation of COOH* intermediate and optimum CO* binding energy. The pyrrolic N regulate the electronic structure of the catalyst, resulting in lower CO 2 adsorption energy and higher intrinsic catalytic activity.