Electrochemical reconstruction: a new perspective on Sn metal-organic complex microbelts as robust anode for lithium storage

Tin-based materials with high theoretical capacity and suitable working voltage are ideal anode materials for lithium-ion batteries(LIBs). However, to overcome their shortcomings(volume expansion and inferior stability), the preparation processes are usually complicated and expensive. Herein, a tin-based metal-organic complex(tin 1,2-benzenedicarboxylic acid, Sn-BDC)with one-dimensional microbelt morphology is synthesized by a facile, rapid and low-cost co-precipitation method, and served as anode material for LIBs without any post-treatment. Sn-BDC exhibits a high reversible capacity with609/440 m Ah·g^(-1) at 50/2000 m A·g^(-1), and robust cycling stability of 856 m Ah·g^(-1) after 200 cycles at 200 m A·g^(-1),which are obviously superior to that of the Sn Ox/C counterparts. Moreover, an electrochemical reconstruction perspective on the lithium storage mechanism of Sn-BDC is proposed by systematic ex-situ characterizations. The reconstructed SnO_(2) replaces Sn-BDC and becomes the active material in the subsequent cycles. As the by-product of the lithiation reaction, the formed Li-based metal-organic complex(Li-BDC, wrapped around the reconstructed SnO_(2)) plays an important role in alleviating volume expansion and accelerating the charge transfer kinetics.This work is beneficial to design and construct the new electrode materials based on the electrochemical reconstruction for advanced LIBs.

High mass loading Ni_(4)Co_(1)-OH@CuO core-shell nanowire arrays obtained by electrochemical reconstruction for alkaline energy storage

The design of three-dimensional(30)core-shell hetercistructures is an efficient method to achieve high mass specific capacity of electroactive materials under high mass loading.In this work,porous Ni_(4)Co1-0H nanosheets with a mass loading of 7.7 mg·cm^(-2) are obtained by using Ni_(4)Cor(NO_(3))_(2)(0H)_(4) supported on the CuO nanowires as precursors via an unavoidable electrochemically induced phase reconstruction.During the electrochemical reconstruction process,the N03-anions in Ni_(4)Cor(N0_(3))_(2)(0H)_(4) are easily replaced by OH-anions in the electrolyte.The phase reconstruction is accompanied by the decrease of ionic diffusion.:resistance and the increase of pore volume,and the shift of binding energy.The obtained Ni4Co1-0H nanosheets show a high:mass specific capacity of 363.6 mAh·g^(-1) at 5 mA·cm^(-2).The as-fabricated alkaline hybrid supercapacitor and Ni-Zn battery deliver high energy density of 293.1 and 604.9 Wh·kg^(-1),respectively,indicating.excellent alkaline energy storage performance.

Electrocatalysis induced reconstruction of RuNiPO for highly efficient hydrogen evolution reaction

Reconstruction during the catalytic process has been considered to play a key role for the performance.Here we report a RuNiPO based catalyst for efficient alkaline hydrogen evolution reaction(HER),which can benefit from a long-term reconstruction during HER for 10 h to continuously increase the performance.The final catalyst(e-RuNiPO)shows a huge morphology change from bulk sphere to highly exposed layered structure in the electrocatalysis process,and exhibits an interesting electronic structure modification with the electron transfer from Ru to Ni for better interfacial interaction and quick charge transfer.Due to the favorable morphology with more exposed active sites and the optimized electronic structure,the final catalyst can achieve an outstanding performance with only an overpotential of 15 mV at 10 mA cm^(-2)(with a good stability more than 100 h),even outperforming the performance of benchmark 20 wt%Pt/C catalyst(18 mV at 10 mA cm^(-2))by using a much lower Ru content.

Retaining the self-released chalcogenate at reconstructed cobalt sites by self-transformed carbonate regulation for boosted oxygen evolution

The in-situ generated oxyanions at electrochemically reconstructed catalysts from metal-based nonoxide compounds have been proven to significantly accelerate oxygen evolution reaction(OER)kinetics.However,it remains a challenge to retain these self-released oxyanions at reconstructed catalysts,hindering its utilization as a tool to develop efficient OER catalysts.Here,we demonstrate a versatile selftransformed carbonate regulation strategy to efficiently retain the self-released chalcogenate at Co oxyhydroxides reconstructed from carbon-incorporated Co selenides under OER conditions.These selftransformed CO_(3)^(2-)can induce electron accumulation and narrow d bond at Co sites to facilitate the Co3d-O 2p orbital hybridization between Co sites and SeO_(x)^(2-)for enhanced SeO_(x)^(2-)retention,which can accelerate the rate-limiting step for^(*)OOH formation during OER.Relative to CoOOH-SeO_(x)^(2-)with limited SeO_(x)^(2-)residues,CoOOH-CO_(3)^(2-)/SeO_(x)^(2-)with elevated SeO_(x)^(2-)retention by CO_(3)^(2-)regulation exhibited a 5.6-fold increase in current density and a remarkable lower Tafel slope towards OER.This strategy paves a rational avenue to design efficient catalysts for electrooxidation reactions through finely regulating self-released oxyanions at reconstructed structures.

Antagonism effect of residual S triggers the dual-path mechanism for water oxidation

Transition metal chalcogenides(TMCs)are recognized as pre-catalysts,and their(oxy)hydroxides derived from electrochemical reconstruction are the active species in the water oxidation.However,understanding the role of the residual chalcogen in the reconstructed layer is lacking in detail,and the corresponding catalytic mechanism remains controversial.Here,taking Cu_(1-x)Co_(x)S as a platform,we explore the regulating effect and existence form of the residual S doped into the reconstructive layer for oxygen evolution reaction(OER),where a dual-path OER mechanism is proposed.First-principles calculations and operando~(18)O isotopic labeling experiments jointly reveal that the residual S in the reconstructive layer of Cu_(1-x)Co_(x)S can wisely balance the adsorbate evolution mechanism(AEM)and lattice oxygen oxidation mechanism(LOM)by activating lattice oxygen and optimizing the adsorption/desorption behaviors at metal active sites,rather than change the reaction mechanism from AEM to LOM.Following such a dual-path OER mechanism,Cu_(0.4)Co_(0.6)S-derived Cu_(0.4)Co_(0.6)OSH not only overcomes the restriction of linear scaling relationship in AEM,but also avoids the structural collapse caused by lattice oxygen migration in LOM,so as to greatly reduce the OER potential and improved stability.

A novel septenary high-entropy(oxy)hydroxide electrocatalyst for boosted oxygen evolution reaction

High-entropy materials(HEMs)have attracted extensive attention in the field of electrochemical catal-ysis due to their unique properties.However,the preparation of high-entropy catalysts typically relies on high-temperature,energy-intensive,and time-consuming synthesis methods due to their compositional complexity.In this study,a facile low-temperature electrochemical reconstruction approach is adopted to synthesize Ag-decorated septenary Co-Cu-Fe-Mo-Zn-Ag-Ru high-entropy(oxy)hydroxide electro-catalysts for oxygen evolution reaction(OER).By introducing Ag and Ru elements and implanting Ag nanoparticles to co-regulate the electronic structure of the catalysts,the as-prepared catalyst achieves remarkable OER performance with a low overpotential of 298 mV at 100 mA/cm^(2)and a small Tafel slope of 30.1 mV/dec in 1 mol/L KOH.This work offers a valuable strategy for developing high-performance high-entropy OER electrocatalysts.

Synergizing high valence metal sites and amorphous/crystalline interfaces in electrochemical reconstructed CoFeOOH heterostructure enables efficient oxygen evolution reaction

Cobalt hydroxide nanosheet is among the most popular oxygen evolution reaction(OER)catalyst yet still suffers from sluggish catalytic kinetics,limited activity,and poor stability.Here,an efficient in situ electrochemical reconstructed CoFe-hydroxides derived OER electrocatalyst was reported.The introduction of Fe promoted the transformation of Co^(2+)into Co^(3+)in CoFehydroxides nanosheet,along with the formation of abundant amorphous/crystalline interfaces.Thanks for the retained nanosheet microstructure,high valence Co^(3+)and Fe^(3+)species,and the amorphous/crystalline heterostructure interfaces,the as-designed electrochemical reconstructed CoFeOOH nanosheet/Ni foam(CoFeOOHNS/NF)electrode delivers 100 mA·cm^(−2) in alkaline at an overpotential of 275 mV and can stably electrocatalyze water oxidation for at least 35 h at 100 mA·cm^(−2).Meanwhile,the alkaline full water splitting electrolyzer achieves a current density of 10 mA·cm^(−2) only at 1.522 V for CoFeOOHNS/NF‖Pt/C/NF,which is much lower than that of Ru/C/NF‖Pt/C/NF(1.655 V@10 mA·cm^(−2)).This work paves the way for in-situ synergetic modification engineering of electrochemical active components.

Crystalline-amorphous interfaces of NiO-CrO_(x)electrocatalysts for boosting the urea oxidation reaction

The overall energy efficiency of electrochemical systems is severely hindered by the traditional anodic oxygen evolution reaction(OER).Utilizing urea oxidation reaction(UOR)with lower thermodynamic potential to replace OER provides a promising strategy to enhance the energy efficiency.Amorphous and heterojunctions electrocatalysts have been aroused extensive studies owing to their unique physicochemical properties and outperformed activity.Herein,we report a simple method to construct a novel crystalline-amorphous NiO-CrO_(x)heterojunction grown on Ni foam for UOR electrocatalyst.The NiO-CrO_(x)electrocatalyst displays excellent UOR performance with an ultralow working potential of 1.32 V at 10 mA·cm^(−2)and ultra-long stability about 5 days even at 100 mA·cm^(−2).In-situ Raman analysis and temperature-programmed desorption(TPD)measurement verify that the presence of the amorphous CrO_(x)phase can boost the reconstruction from NiO to active NiOOH species and enhance adsorption ability of urea molecule.Besides,the unique crystalline-amorphous interfaces are also benefit to improving the UOR performance.

Ni_(3)S_(2)@NiFePx electrode with dual-anion-modulated layer for efficient and stable oxygen evolution

The rational construction of high-performance and stable electrocatalyst for oxygen evolution reaction(OER)is a prerequisite for efficient water electrolysis.Herein,we develop a broccoli-like Ni_(3)S_(2)@NiFeP_(x)(Ni_(3)S_(2)@NFP)catalyst on nickel foam(NF)via a sequential two-step layer-by-layer assembly electrodeposition method.X-ray diffraction,in situ Raman and Fourier-transform infrared spectra have mutually validated the element segregation and phase refusion during OER condition.The reconstruction of double layer Ni_(3)S_(2)@NFP facilitates the formation of the active(oxy)hydroxides,which is modulated by the dual anionic layer with mixed sulfate and phosphate ions.As a result,the obtained Ni_(3)S_(2)@NFP electrode exhibits low overpotential(329 mV)and long-term durability(∼500 h)for OER at current density of 500mA/cm^(2).Moreover,the self-supported Ni_(3)S_(2)@NFP can act as an efficient and durable anode in alkaline anion exchange membrane water electrolysis device(AEMWE).This work provides a facile and scaled-up strategy to construct self-supported electrocatalyst and emphasizes the crucial role of anions in pre-catalyst reconstruction and enhancing OER performance.