Application Study Of Non-noble Metal Catalyst Based On Gel Method In Oxygen Precipitation Reaction And Dye Wastewater Degradation

Sol-gel method is widely used as an important synthetic method to prepare nanocatalysts.The colloidal system of commercial gel materials can form a continuous network skeleton,providing a large number of pore-shaped spaces inside the material.Currently gel materials have been widely used in various fields,such as the conversion and storage of electrocatalytic energy,and the catalytic degradation of dye wastewater.The electrocatalytic water decomposition reaction is composed of a cathodic hydrogen evolution reaction（HER）and an anodic oxygen evolution reaction（OER）.Due to the high reaction barrier results in a low reaction rate and excessive energy consumption.It is necessary to study the synthesis of high-performance catalysts to increase the reaction rate.Thus,the development of low-cost,high-performance non-precious metal electrocatalysts has become a research hotspot in recent years.Among them,transition metal nickel（Ni）and iron（Fe）based catalysts are widely concerned because of their excellent OER activity.In printing and dyeing wastewater,RhB（rhodamine B）is a common organic pollutant.Due to its strong antioxidant and photodegradation resistance,it is difficult to degrade using conventional methods.The new advanced oxidation technology based on persulfate has considerable prospects in the field of refractory organic wastewater.Because the process of persulfate directly decomposing free radicals to degrade organic pollutants is slow,and the efficiency is low,a method of adding catalysts to activate the degradation of persulfate is spawned.Among them,SO₄^·-and other strong oxidizing radicals generated during the transition metal activation process can efficiently degrade organic pollutants.In response to the above problems,this paper mainly includes the following parts:（1）A series of Ni_xFe-gel nanocatalysts with different ratios were synthesized by the modified permeation gel method,and the influence of Fe and Ni ratio on the catalytic activity and stability of OER was discussed.Transmission electron microscopy（TEM）and Brunauer-Emmett-Teller（BET）characterization show that Ni_xFe-gel has a large number of micropores that provide a large specific surface area,which help to improve the OER activity of the catalyst.Electrochemical tests show that the optimal ratio of Ni_2.0Fe-gel has excellent OER performance（245 m V）in 1 M KOH,and the stability test can reach 11.6 hours at a current density of 10 m A cm^-2,better than commercial catalyst Ru O₂.（2）The synthesized transition metal catalyst is used to activate the persulfate,and the sulfate radical is used to oxidatively degrade Rh B in the printing and dyeing wastewater.Due to the special three-dimensional network structure of the catalyst,there are a lot of voids inside,which makes the catalytic active surface area higher and the activation performance better.The Fe Co W-gel developed in this paper degrades Rh B at a concentration of 20μmol·L^-1at room temperature to reach 1.05 min^-1.After repeated degradation for 6 times still has high activation performance.Subsequent further mechanism investigations showed that single-line oxygen occupies a dominant role in the system,along with hydroxyl radicals and sulfate radicals.