Multiple structural defects in ultrathin NiFe-LDH nanosheets synergistically and remarkably boost water oxidation reaction

Modifying electrocatalysts nanostructures and tuning their electronic properties through defects-oriented synthetic strategies are:essential to improve the oxygen evolution reaction(OER)performance of electrocatalysts.Current synthetic strategies about.electrocatalysts mainly target the single or double structural defects,while the researches about the synergistic effect of multiple'structural defects are rare.In this work,the ultrathin NiFe layered double hydroxide nanosheets with a holey structure,oxygen;vacancies and Ni^(3+)defects on nickel foam(NiFe-LDH-NSs/NF)are prepared by employing a simple and green H202-assisted etching 1 method.The synergistic effect ofthe above three defects leads to the exposure of.more active sites and significant improvement of:the intrinsic activity.The optimized catalyst exhibits an excellent OER performance with an extraordinarily low overpotential of 170 mV;at to mA·cm^(-2) and a small Tafel slope of 39.3 mV·dec^(-1) in 1 M KOH solution.Density functional theory calculations reveal this OER;performance arises from pseudo re-oxidized metal-stable Ni^(3+)near oxygen vacancies(O_(vac)),which suppresses 3d-e_(g) of Ni-site and!elevates d-band center towards the competitively low electron-transferbarrier.This work provides a new insight to fabricate advanced electrocatalysts for renewable energy conversion technologies.

One-pot pyrolysis synthesis of highly active Ru/RuOx nanoclusters for water splitting

Using simple methods to obtain efficient catalysts has been a long-standing goal for researchers.In this work,the employment of a one-pot pyrolysis reaction to achieve molecular confinement,has led to the preparation of ruthenium(Ru)-based nanoclusters in a carbon matrix.A unique feature of the synthetic approach employed is that solvent and substrates were calcined together.As solvent evaporates,during calcination,the substrates form a dense solid which has the effect of limiting the aggregation of Ru centers during the carbonization process.The catalyst prepared in this simple manner showed an impressively high activity with respect to the hydrogen/oxygen evolution reaction(HER/OER).The Ru nanoclusters(Ru NCs),as the hydrogen evolution reaction(HER)catalysts,require ultralow overpotentials of 5 mV and 5.1 mV at-10 mA·cm^(-2) in 1.0 M KOH,and 0.5 M H_(2)SO_(4),respectively.Furthermore,the catalyst prepared by the one-pot method has higher crystallinity,a higher Ru content and an ultrafine cluster size,which contributes to its exceptional electrochemical performance.Meanwhile,the RuO_(x) nanoclusters(RuO_(x) NCs),obtained by oxidizing the aforementioned Ru NCs,exhibited good oxygen evolution reaction(OER)performance with an overpotential of 266 mV at 10 mA·cm^(-2).When applied to overall water splitting,Ru/RuO_(x) nanoclusters as the cathode and anode catalysts can reach 10 mA·cm^(-2) at cell voltages of only 1.49 V in 1 M KOH.