A robust & weak-nucleophilicity electrocatalyst with an inert response for chlorine ion oxidation in large-current seawater electrolysis

Seawater splitting into hydrogen,a promising technology,is seriously limited by the durability and tolerance of electrocatalysts for chlorine ions in seawater at large current densities due to chloride oxidation and corrosion.Here,we present a robust and weak-nucleophilicity nickel-iron hydroxide electrocatalyst with excellent selectivity for oxygen evolution and an inert response for chlorine ion oxidation which are key and highly desired for efficient seawater electrolysis.Such a weak-nucleophilicity electrocatalyst can well match with strong-nucleophilicity OH-compared with the weak-nucleophilicity Cl^(-),resultantly,the oxidation of OH-in electrolyte can be more easily achieved relative to chlorine ion oxidation,confirmed by ethylenediaminetetraacetic acid disodium probing test.Further,no strongly corrosive hypochlorite is produced when the operating voltage reaches about 2.1 V vs.RHE,a potential that is far beyond the thermodynamic potential of chlorine ion oxidatio n.This concept and approach to reasonably designing weaknucleophilicity electrocatalysts that can greatly avoid chlorine ion oxidation under alkaline seawater environments can push forward the seawater electrolysis technology and also accelerate the development of green hydrogen technique.

Controllable surface reconstruction of copper foam for electrooxidation of benzyl alcohol integrated with pure hydrogen production

Electrocatalytic water splitting that is coupled with electrocatalytic chemical oxidation is considered as one of the promising methods for efficiently obtaining hydrogen energy and fine chemicals.Herein,we focus on an electrochemical redox activation strategy to rationally manipulate the microstructure and surface valence states of copper foam(CF)and boost the corresponding performance towards electrocatalytic benzyl alcohol oxidation(EBA),accompanied by the efficient hydrogen production.Correspondingly,the Cu(II)‐dominated species are gradually formed on the CF surface with the dissolution and redeposition of copper in the suitable potential range.The new species containing Cu2O,CuO,and Cu(OH)2 during surface reconstruction process of the CF were confirmed by multiple characterization techniques.After 220‐cycled activation(CF‐220),the activated CF achieves an increase of current density for EBA in anode from 9.5 for the original CF to 29.3 mmol/cm2,while the pure hydrogen yield increases threefold than that of the original CF at 1.5 VRHE.The produced new species can endow the CF‐220 with abundant acidity sites,which can enhance the adsorption toward Lewis‐basicity benzyl alcohol,confirmed by NH3‐temperature‐programmed desorption.In situ Raman result further reveals that the as‐produced CuO,Cu(OH)2,and Cu(OH)42−are the main active species toward the EBA process.

Enhanced water-induced effects enabled by alkali-stabilized Pd-OH_(x) species for oxidation of benzyl alcohol

The water promotion effects,where water can provide a solution-mediated reaction pathway in various heterogeneous chemical catalysis,have been presented and attracted wide attention recently,yet,the rational design of catalysts with a certain ability of enhancing water-induced reaction process is full of challenges and difficulties.Here,we show that by incorporating alkali(Na,K)cations as an electronic and/or structural promoter into Pd/rGO-ZnCr_(2)O_(4)(r GO,reduced graphene oxide),the obtained Pd(Na)/rGO-ZnCr_(2)O_(4)as a representative example demonstrates an outstanding benzyl alcohol oxidation activity in the Pickering emulsion system in comparison to the alkali-free counterpart.The response experiments of water injection confirm the enhanced activity,and the Na-modified catalyst can further enhance the promotion effects of water on the reaction.The effects of alkali cations for Pd nanoparticles are identified and deciphered by a series of experimental characterizations(XPS,in situ CO-DRIFTS,and CO-TPR coupled with MS),showing that there is abundant-OH on the surface of the catalyst,which is stabilized by the formation of Pd-OH_(x).The alkali-stabilized Pd-OH_(x)is helpful to enhance the waterinduced reaction process.According to the results of in situ Raman as well as UV-vis absorption spectra,the Na-modulated Pd(Na)/rGO-ZnCr_(2)O_(4)enables the beneficial characteristics for distorting the benzyl alcohol structure and enhancing the adsorption of benzyl alcohol.Further,the mechanism for enhanced water promotion effects is rationally proposed.The strategy of alkali cations-modified catalysts can provide a new direction to effectively enhance the chemical reaction involving small molecule water.