Cathodic corrosion as a facile and universal method for scalable preparation of powdery single atom electrocatalysts

Top-down strategy has been widely applied for synthesis of metal single atom catalysts(SACs)via converting metal nanoparticles or bulk metals into atomically dispersed species.Here,we report a simple electrochemical atomic migration strategy for top-down synthesis of SACs via a facile cathodic corrosion process without involving high temperature or harsh atmosphere.Atoms of metal nanoparticles on cathode are firstly disbanded under high negative voltage,and emitted into the electrolyte in the form of atomic metal anions in Zintl phase.The escaped atomically dispersed metal species are then oxidized by water molecules and captured by the defects on the pre-added nitrogen doped carbon carriers in the electrolyte.This cathodic corrosion strategy is confirmed to be suitable for scalable synthesis of kinds of metal SACs(e.g.,Pt,Pd,and Ir)on doped carbon materials.Typically,the as-prepared nitrogen doped carbon powder supported Pt SACs exhibit superior catalytic activity toward hydrogen evolution reaction(HER)with a low overpotential of 0.024 V at 10 mA·cm^(−2)and a low Tafel slope of 29.7 mV·dec^(−1)as well as a long-term durability.

Improved field emission properties of carbon nanotube cathodes by nickel electroplating and corrosion

Carbon nanotube（CNT） cathodes prepared by electrophoretic deposition were treated by a combination of nickel electroplating and cathode corrosion technologies.The characteristics of the samples were measured by scanning electron microscopy,energy dispersive X-ray spectroscopy,J-E and F-N plots.After the treatment,the CNT cathodes showed improved field emission properties such as turn-on field,threshold electric field,current density,stability and luminescence uniformity.Concretely,the turn-on field decreased from 0.95 to 0.45 V/μm at an emission current density of 1 mA/cm^2,and the threshold electric field decreased from 0.99 to 0.46 V/μm at a current density of 3 mA/cm^2.The maximum current density was up to 7 mA/cm2 at a field of 0.48 V/μm.In addition,the current density of the CNT cathodes fluctuated at around 0.7 mA/cm^2 for 20 h,with an initial current density 0.75 mA/cm^2.The improvement in field emission properties was found to be due to the exposure of more CNT tips,the wider gaps among the CNTs and the infiltration of nickel particles.

Electrochemical synthesis of catalytic materials for energy catalysis

Electrocatalysis is a process dealing with electrochemical reactions in the interconversion of chemical energy and electrical energy.Precise synthesis of catalytically active nanostructures is one of the key challenges that hinder the practical application of many important energy‐related electrocatalytic reactions.Compared with conventional wet‐chemical,solid‐state and vapor deposition synthesis,electrochemical synthesis is a simple,fast,cost‐effective and precisely controllable method for the preparation of highly efficient catalytic materials.In this review,we summarize recent progress in the electrochemical synthesis of catalytic materials such as single atoms,spherical and shaped nanoparticles,nanosheets,nanowires,core‐shell nanostructures,layered nanomaterials,dendritic nanostructures,hierarchically porous nanostructures as well as composite nanostructures.Fundamental aspects of electrochemical synthesis and several main electrochemical synthesis methods are discussed.Structure‐performance correlations between electrochemically synthesized catalysts and their unique electrocatalytic properties are exemplified using selected examples.We offer the reader with a basic guide to the synthesis of highly efficient catalysts using electrochemical methods,and we propose some research challenges and future opportunities in this field.

Cathodic corrosion as a facile and universal method for the preparation of supported metal single atoms

Top-down strategy has been generally adopted for preparation of metal single atom catalysts(SACs)due to the simplified synthetic process,metal economics,and scalability characteristics.Herein,we propose a general top-down route to convert metal nanoparticles into uniformly dispersed metal single atoms in mild electrochemical environment via a facile cathodic corrosion process.Within the synthetic process,Pt nanoparticles precursors are transformed into migrating Pt single atoms(Pt1)driven by a high negative potential;and subsequently these mobile Pt atoms are trapped and stabilized by N coordination sites of N-doped carbon paper(NCP).The as-prepared Pt1/NCP electrodes exhibit a superior catalytic activity toward hydrogen evolution reaction(HER)with a low overpotential of 0.022 V at 10 mA/cm^(2)and a low Tafel slope of 28.5 mV/dec as well as a long-term durability.Notably,the proposed electrochemical atomic migration strategy shows a promising generality for fabricating other metal single atoms(e.g.,Pd,Ir,Cu),which may open a new avenue for metallic SACs preparation.