Activity origin and alkalinity effect of electrocatalytic biomass oxidation on nickel nitride

Electro-oxidation of 5-hydroxymethylfurfural(HMFOR)is a promising green approach to realize the conversion of biomass into value-added chemicals.However,considering the complexity of the molecular structure of HMF,an in-depth understanding of the electrocatalytic behavior of HMFOR has rarely been investigated.Herein,the electrocatalytic mechanism of HMFOR on nickel nitride(Ni3 N)is elucidated by operando X-ray absorption spectroscopy(XAS),in situ Raman,quasi in situ X-ray photoelectron spectroscopy(XPS),and operando electrochemical impedance spectroscopy(EIS),respectively.The activity origin is proved to be Ni^(2+δ)N(OH)ads generated by the adsorbed hydroxyl group.Moreover,HMFOR on Ni3 N relates to a two-step reaction:Initially,the applied potential drives Ni atoms to lose electrons and adsorb OH-after 1.35 VRHE,giving rise to Ni^(2+δ)N(OH)ads with the electrophilic oxygen;then Ni^(2+δ)N(OH)ads seizes protons and electrons from HMF and leaves as H_(2) O spontaneously.Furthermore,the high electrolyte alkalinity favors the HMFOR process due to the increased active species(Ni^(2+δ)N(OH)ads)and the enhanced adsorption of HMF on the Ni3 N surface.This work could provide an in-depth understanding of the electrocatalytic mechanism of HMFOR on Ni3 N and demonstrate the alkalinity effect of the electrolyte on the electrocatalytic performance of HMFOR.

Activity Origins of Graphdiyne Based Bifunctional Atom Catalysts for Hydrogen Evolution and Water Oxidation

Graphdiyne(GDY)based atom catalysts(ACs)show extraordinary electrocatalytic activities towards hydrogen evolution reaction(HER)and water oxidation reaction(OER),which have attracted wide attention of scientists.However,a precise understanding on the activities trends and origins of ACs is still under exploration.We investigate the electrocatalytic performance of a series of ACs in this work.Density functional theory(DFT)calculations reveal that the half reactions of OER and HER are site-dependent on ACs,which are preferentially proceeded on the metal site and the nearby bonded carbon site,respectively.Besides,the d-band center of metal atoms is the most important descriptor,which can perfectly correlate the high activities of ACs towards the two half reactions.Especially for HER,the deeper d-band position of metal atoms corresponds to much stronger d-p_(x)(p_(y))orbital coupling in ACs,which activate more obvious charge transfer between the metal site and the nearby bonded carbon site,resulting in the HER activity enhancement of ACs.These results are of great significance in guiding the precise synthesis of highly efficient bifunctional metal atom catalysts supported by GDY in future.

Tidally disrupted dusty clumps as the origin of broad emission lines in active galactic nuclei

With the support by the National Natural Science Foundation of China,a collaboration led by Prof.Wang Jianmin(王建民)from the Institute of High Energy Physics,Chinese Academy of Sciences proposes a new mechanism for the origin of the broad-line region in Active Galactic Nuclei,which was published

AN ORIGINAL DIAGNOSTIC SYSTEM FOR MALARIA TO SCREEN THE ANTIPLASMODIAL ACTIVITY OF AFRICAN HERBAL MEDICINES

Malaria,caused by protozoa of the genus Plasmodium,causes some 198 million of confirmed cases and about584,000 of deaths per year.Its management needs both accurate diagnostic and treatments availability.The current diagnostic techniques(rapid diagnostic tests and microscopy)appear either too expensive,lowly sensitive or difficult to implement.The hemozoin('malaria pigment')