MXene boosted MOF-derived cobalt sulfide/carbon nanocomposites as efficient bifunctional electrocatalysts for OER and HER.

The development of effective bifunctional electrocatalysts that can realize water splitting to produce oxygen and hydrogen through oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) is still a great challenge to be addressed. Herein, we report a simple and versatile approach to fabricate bifunctional OER and HER electrocatalysts derived from ZIF67/MXene hybrids via sulfurization of the precursors in hydrogen sulfide gas atmosphere at high temperatures. The as-prepared CoS@C/MXene nanocomposites were characterized using a series of technologies including X-ray diffraction, gas sorption, scanning electronic microscopy, transmission electronic microscopy, energy dispersive spectroscopy, and X-ray photoelectron spectroscopy. The synthesized CoS@C/MXene composites are electrocatalytically active in both HER and OER, and the CSMX-800 composite displayed the highest electrocatalytic performance towards OER and HER among all the produced samples. CSMX-800 exhibited overpotentials of 257 mV at 10 mA cm-2 for OER and 270 mV at 10 mA cm-2 for HER. Moreover, it also possesses small Tafel slope values of 93 mV dec-1 and 103 mV dec-1 for OER and HER, respectively. The enhanced electrocatalytic performance of the MXene-containing composites is due to their high surface area, enhanced conductivity, and faster charge transfer. This work demonstrated that CoS@C/MXene based electrocatalyst has great potential in electrochemical water splitting for hydrogen production, thus reducing carbon emissions and protecting the environment.

Perovskite LaNiO3/Ag3PO4 heterojunction photocatalyst for the degradation of dyes.

Pristine lanthanum nickelate (LaNiO3), silver phosphate (Ag3PO4) and perovskite lanthanum nickelate silver phosphate composites (LaNiO3/Ag3PO4) were prepared using the facile hydrothermal method. Three composites were synthesized by varying the percentage of LaNiO3 in Ag3PO4. The physical properties of as-prepared samples were studied by powder X-ray diffraction (pXRD), Fourier-transform infrared (FT-IR), Scanning electron microscopy (SEM) and Energy-dispersive X-ray (EDX). Among all synthesized photocatalysts, 5%LaNiO3/Ag3PO4 composite has been proved to be an excellent visible light photocatalyst for the degradation of dyes i.e., rhodamine B (RhB) and methyl orange (MO). The photocatalytic activity and stability of Ag3PO4 were also enhanced by introducing LaNiO3 in Ag3PO4 heterojunction formation. Complete photodegradation of 50 mg/L of RhB and MO solutions using 25 mg of 5%LaNiO3/Ag3PO4 photocatalyst was observed in just 20 min. Photodegradation of RhB and MO using 5%LaNiO3/Ag3PO4 catalyst follows first-order kinetics with rate constants of 0.213 and 0.1804 min-1, respectively. Perovskite LaNiO3/Ag3PO4 photocatalyst showed the highest stability up to five cycles. The photodegradation mechanism suggests that the holes ( h +) and superoxide anion radicals O 2 • - plays a main role in the dye degradation of RhB and MO.

Silane-Grafted MXene (Ti3C2T X ) Membranes for Enhanced Water Purification Performance.

The current communication describes the modifications of MXene (Ti3C2T x ) with silane grafting reaction for membrane preparation for enhanced water purification. The MXene was successfully grafted with n-octadecyltrichlorosilane (MODCS), n-octyltrichlorosilane (MNOCS), and triphenylchlorosilane (MTPCS) in order to make a hydrophobic MXene that could be able to bind with the organic matrix/polymers. The modified MXenes were transformed into thin membranes by forming an MXene/polyvinyl alcohol (PVA) composite over a filter paper support, that is, MCE (mixed cellulose ester filter paper). MXene membranes were also formed without the MCE support by using PVA and glutaraldehyde (PVA/GA) where GA was used as a cross-linker to stabilize PVA and make it water-resistant. The conditions of membrane formation were optimized to investigate optimum compatible conditions with the modified materials. The resulting membranes were tested for the removal of various organic pollutants that included mesitylene (or trimethylbenzene); polyaromatic hydrocarbons (chrysene, as a model); biphenyl; bisphenol A; benzene, toluene, ethylbenzene, and styrene; methylene blue; and Sudan II dyes. The MTPCS PVA/GA cross-linked membrane showed the best results for a pollutant removal efficiency up to 98%. Overall, all six types of membranes showed the removal efficiency in the range of 52-98%. It was observed that the membrane exhibits reusability up to five cycles.