Controllable Synthesis Of Transition Metal Chalcogenides And Their Photocatalysis/Electrocatalysis Performance

The environmental pollution and energy crisis resulting from fossil fuel combustion are increasingly serious.Photocatalytic degradation and electrocatalytic water-splitting,as the ever greenest and scale-up easily techniques,have aroused great interest around the world.The industry scale-up applications of noble metal catalysts,however,are dramatically limited by their expensive price and scarcity.Transition metal chalcogenides,a class of earth-abundant material,have been proved to be the excellent performance in photocatalysis and electrocatalysis fields.The research topics of this paper are mainly focus on the preparation of transition metal chalcogenides and their hybrid materials for photocatalytic degradation or electrocatalytic water-splitting.The main research contents are as below:1.Dandelion-like ZnS was synthesized via a facile hydrothermal method,and then as the support to further synthesize dandelion-like ZnS/carbon quantum dot hybrid materials.The photocatalytic activities of the as-prepared materials were investigated by the photodegradation of methylene blue,Rhodamine B and the colorless antibiotic ciprofloxacin hydrochloride,respectively.The as-synthesized hybrid materials exhibit higher photocatalytic activity than that of the pure ZnS under simulated sunlight(?>380 nm),indicating a broad-spectrum of photocatalytic degradation activity.The most beneficial amount of carbon quantum dots to improve the photocatalytic activity of the ZnS is 2 wt.%.2.We report the synthesis of a Co-doped nickel selenide(a mixture of NiSe2 and Ni3Se4)/C hybrid nanostructure supported on Ni foam using a metal-organic framework as the precursor.The resulting catalyst exhibits excellent catalytic activity toward the oxygen evolution reaction(OER),which only requires an overpotential of 275 mV to drive a current density of 30 mA cm-2.This overpotential is much lower than those reported for precious metal free OER catalysts.The hybrid is also capable of catalyzing the hydrogen evolution reaction(HER)efficiently.A current density of 10 mA cm-2 can be achieved at 90 mV.In addition,such a hybrid nanostructure can achieve 10 at potentials of 1.6 V,along with good durability when functioning as both the cathode and the anode for overall water splitting in basic media.3.We combined several methods of enhancing the exposed active sites of the catalysts into a facile synthesis strategy to obtain the 3D hollow(Ni,Co)Se2/carbon polyhedral.Thanks to the unique hollow structure and the sheet-assembled edge-to-face stacking shells,the obtained(Ni,Co)Se2/C-HRD shows superior catalytic activities toward the hydrogen evolution reaction(HER)and oxygen evolution reaction(OER),which only needs an overpotential of 87 mV at 10 mA cm-2 for HER and an overpotential of 270 mV to deliver 20 mA cm-2 for OER.More importantly,when used as both the anode and cathode for full water splitting,a cell voltage as low as 1.58 V is needed to reach the current density of 10 mA cm-2,making(Ni,Co)Se2/C-HRD as a promising alternative to noble metal catalysts for water splitting.