In-situ evolution process understanding from a salan-ligated manganese cluster to supercapacitive application

The goal of material chemistry is to study the relationship among hierarchical structure,chemical reaction and precision preparation for materials,yet tracking pyrolysis process on multi-dimensional scale is still at primary stage.Here we propose packing mode analysis to understand evolution process in high temperature reaction.As a proof of concept,we first design a salan-ligated Mn3(Mn3(3-MeOsalophen)_(2)(Cl)_(2))cluster and pyrolyze it under an inert atmosphere directly to a mixed valence MnOx embedded in a porous N-doped carbon skeleton(MnOx/C).Meanwhile,combining thermogravimetry-mass spectrometry(TG-MS)with other characterization techniques,its pyrolysis process is precisely tracked real-time and Mn^(2+)/Mn^(3+)ratios in the resulting materials are deduced,ensuring excellent electrochemical advantages.As a result,the as-preferred MnOVC-900 sample reaches 943 F/g at 1 A/g,maintaining good durability under 5,000 cycles with 90%retention.The highlight of packing mode analysis strategy in this work would provide a favorable approach to explore the potential relationship between structure and performance in the future.

Model Compounds of the Mn Cluster in Oxygen-evolving Complex of PSⅡ

Six model compounds have been synthesized and used for probing the structural features of the Mn cluster in oxygen_evolving complex (OEC) of photosystem Ⅱ (PSⅡ). The model compounds contain Mn 2(μ_O) 2 and μ_O_μ_carboxylato di_manganese structural units, which offer Mn—Mn, Mn……Mn, and Mn—O(N) structural parameters consistent with the corresponding data of the OEC in PSⅡ, implying that the Mn cluster in OEC may possess similar structural features. Two model compounds containing halide anion have been used for discussing the binding of Cl - to Mn in PSⅡ. It is suggested that in the five S states, ligand exchange would lead to the ligation of chloride to Mn in the S states with Mn of higher valence.

Regulated adsorption sites using atomically single cluster over biochar for efficient elemental mercury uptake

Carbon-based materials have been widely used in gaseous pollutant removal because of their sufficient surface functional groups;however,its removal efficiency for elemental mercury(Hg^(0))is low.In this study,we fabricated biomass using a chelated coupled pyrolysis strategy and further constructed the regulated adsorption sites for gaseous Hg^(0) uptake.A series of Mnδ-N_(2)O_(2)/BC with different manganese cluster sizes demonstrated that manganese clusters anchored on biochar acted as highly active and durable adsorbents for Hg^(0) immobilization,which increased the adsorption efficiency of Hg^(0) by up to 50%.Shrimp-and crab-based biochar adsorbents exhibited excellent Hg^(0) removal because of their chitosan-like structure.In particular,small Mn clusters and oxygen species around the defect led to a boost in the Hg^(0) adsorption by carbon.The results of density functional theory calculation revealed that the presence of oxygen in the carbon skeleton can tune the electrons of small-sized Mn clusters,thereby promoting the affinity of mercury atoms.The newly developed Mnδ-N_(2)O_(2)/BC_(shrimp) had an adsorption capacity of 7.98-11.52 mg g^(−1) over a broad temperature range(50-200℃)and showed a high tolerance to different industrial flue gases(H_(2)O,NO,HCl,and SO_(2)).These results provide novel green and low-carbon disposal methods for biomass resource utilization and industrial Hg^(0) emission control.

Ring-Shaped Polyoxometalate Built by {Mn_(4)PW_(9)} and PO_(4) Units for Efficient Visible-Light-Driven Hydrogen Evolution

A novel mixed-valence,ring-shaped multinuclear Mn-containing polyoxometalate,[H_(2)N(CH_(3))_(2)]_(15) NaH8-[Mn^(Ⅲ) 3MnIV(μ3-O)_(3)(OAc)PO4(B-α-PW_(9)O_(34))]_(4)·36H_(2)O(1)was made and systematically characterized using various spectroscopic and computational techniques.Its polyoxoanion can be described as a tetramer made of four[Mn^(Ⅲ) 3MnIV(μ3-O)3(OAc)(B-α-PW_(9)O_(34))]_(3)−({Mn^(Ⅲ) 3Mn^(IV)(PW_(9))})clusters and four PO_(4) linkers.