Defect engineering in transition-metal(Fe,Co,andNi)-based electrocatalysts for water splitting

Electrocatalytic water splitting seems to be an efficient strategy to deal with increasingly serious environmental problems and energy crises but still suffers from the lack of stable and efficient electrocatalysts.Designing practical electrocatalysts by introducing defect engineering,such as hybrid structure,surface vacancies,functional modification,and structural distortions,is proven to be a dependable solution for fabricating electrocatalysts with high catalytic activities,robust stability,and good practicability.This review is an overview of some relevant reports about the effects of defect engineering on the electrocatalytic water splitting performance of electrocatalysts.In detail,the types of defects,the preparation and characterization methods,and catalytic performances of electrocatalysts are presented,emphasizing the effects of the introduced defects on the electronic structures of electrocatalysts and the optimization of the intermediates'adsorption energy throughout the review.Finally,the existing challenges and personal perspectives of possible strategies for enhancing the catalytic performances of electrocatalysts are proposed.An in-depth understanding of the effects of defect engineering on the catalytic performance of electrocatalysts will light the way to design high-efficiency electrocatalysts for water splitting and other possible applications.

Assessment of the Performances of Carboxylic Acid Monomers as Fluid Loss Additives for Oil-Well Cement

The application of polycarboxylic acid as a fluid loss additive for cement(i.e.,a substance specifically designed to lower the volume of filtrate that passes through the cement)can prolong the thickening time of cement slurries.Given the lack of data about the effects of carboxylic acid monomers as possible components for the additives traditionally used for oil-well cement,in this study different cases are experimentally investigated considering different types of these substances,concentrations,temperatures,and magnesium ion contamination.The results demonstrate that itaconic acid has a strong retarding side effect,while maleic and acrylic acids have similar influences on the thickening time of the cement slurry.The rheological properties of the cement slurry tend to deteriorate when the carboxylic acid monomer content in the fluid loss additive is increased to 40%.If the temperature exceeds 80°C,there is a significant decrease in the related impact on the thickening duration.With an increase in the intrusion of magnesium ions to>0.5%,both the rheological properties of the cement slurry and the thickening time are affected in a negative way.

In situ decorating the surface and interlayer of montmorillonite with Co_(0.5)Ni_(0.5)Fe_(2)O_(4) nanoparticles: A sustainable, biocompatible colorimetric platform for H_(2)O_(2) and acetylcholine

Originated from nature and used for nature is a way of sustainable development.In this work,montmorillonite(MMT),a natural two-dimensional(2D)layered mineral,the surface and interlayer of which were nano-decorated by chemical synthesis technique was applied in biological detection field.Magnetic ferrite(Co_(0.5)Ni_(0.5)Fe_(2)O_(4))was anchored on the surface and intercalated in the interlayer of montmorillonite,which served as a competitive candidate of enzyme mimics.Cytotoxicity test toward HUVEC and Hela cells verified the good biocompatibility of Co_(0.5)Ni_(0.5)Fe_(2)O_(4)-MMT,guaranteeing its safety in biological applications.Based on the peroxidase-like activity of Co_(0.5)Ni_(0.5)Fe_(2)O_(4)-MMT,a colorimetric sensing platform for H_(2)O_(2) was established by a facile mix-anddetect approach with the detection limit of 0.565μM(3σ/slope).It was implied that the peroxidase-like activity of Co_(0.5)Ni_(0.5)Fe_(2)O_(4)-MMT was originated from generation of·OH and·O_(2)–produced from catalytic decomposition process of H_(2)O_(2).Coupled with cascaded catalytic reactions of ACh,a facile and efficient sensing platform for ACh with satisfactory anti-interference ability was established.Thus,all these remarkable features highlighted the superiority of Co_(0.5)Ni_(0.5)Fe_(2)O_(4)-MMT,and endowed it with a powerful competitiveness in the fields of environmental assessing,biosensing,and disease monitoring.