Lignin-based materials for electrochemical energy storage devices

Lignin is the most abundant aromatic polymer in nature,which is rich in a large number of benzene ring structures and active functional groups.The molecular structure of lignin has unique designability and controllability,and is a class of functional materials with great application prospects in energy storage and conversion.Here,this review firstly focuses on the concept,classification,and physicochemical property of lignin.Then,the application research of lignin in the field of electrochemical storage materials and devices are summarized,such as lignin-carbon materials and lignin-carbon composites in supercapacitors and secondary batteries.Finally,this review points out the bottlenecks that need to be solved urgently and the prospects for future research priorities.

Phosphorous and selenium tuning Co-based non-precious catalysts for electrosynthesis of H_(2)O_(2)in acidic media

Electrosynthesis of hydrogen peroxide(H2O2)is an on-site method that enables independent distribution applications in many fields due to its small-scale and sustainable features.The crucial point remains developing highly active,selective and cost-effective electrocatalysts.The electrosynthesis of H2O2 in acidic media is more practical owing to its stability and no need for further purification.We herein report a phosphorus and selenium tuning Co-based non-precious catalyst(CoPSe)toward two-electron oxygen reduction reaction(2e–ORR)to produce H2O2 in acidic media.The starting point of using both P and Se is finding a balance between strong ORR activity of CoSe and weak activity of CoP.The results demonstrated that the CoPSe catalyst exhibited the optimized 2e–ORR activity compared with CoP and CoSe.It disclosed an onset potential of 0.68 V and the H2O2 selectivity 76%-85%in a wide potential range(0–0.5 V).Notably,the CoPSe catalyst overcomes a significant challenge of a narrow-range selectivity for transitionmetal based 2e–ORR catalysts.Finally,combining with electro-Fenton reaction,an on-site system was constructed for efficient degradation of organic pollutants.This work provides a promising non-precious Co-based electrocatalyst for the electrosynthesis of H2O2 in acidic media.

Coulometric Response of H-Selective Solid-Contact Ion-Selective Electrodes and Its Application in Flexible Sensors+

The analytical performance of H+-selective solid-contact ion-selective electrodes(SCISEs)based on solid contact polyaniline doped with chloride(PANI(Cl))and poly(3,4-ethylenedioxythiophene)doped with poly(styrene sulfonate)(PEDOT(PSS))was characterized by a developed coulometric signal transduction method.PEDOT(PSS)solid contact is covered by PVC based H+-selective membrane.The obtained coulometric signal demonstrates that the cumulated charge can be amplified by increasing the capacitance of solid contact.SCISEs covered with spin-coated membrane behave faster amperometric response than electrodes with drop-cast mem-brane.In contrast to earlier works,the amperometric response and impedance spectrum demonstrates H+transfer through SCISEs is independent from the thickness of membrane.The exceptional behavior of PANI(Cl)H+-SCISEs shows that the capacitance estimated from impedance spectrum at low frequency 10 mHz and coulometric signal of PANI(Cl)based SCISEs is influenced by the applied po-tentials,whereas PEDOT(PSS)solid contact is independent from the chosen applied potentials.Furthermore,preliminary investiga-tions of coulometric signal transduction on flexible pH sensor implies its potential applications in wearable sensors for sweat ion concentration detection.

Bimetallic NiCoP catalysts anchored on phosphorus-doped lignin-based carbon for robust oxygen evolution performance

Oxygen evolution reaction(OER)catalysts are the key core materials that determine the performance of fuel cells,metal-air batteries,electrolytic water decomposition,and other applications.In this work,a green lignin-based non-precious metal OER catalyst was prepared by a simple strategy.Firstly,c arboxylated lignin was used to complex Ni and Co in situ,and then they were placed with sodium hypophosphite in the same tube furnace for upstream and downstream high-temperature calcination to construct a lignin carbon-based Ni-Co bimetallic OER catalyst(NiCoP@C).The synthesized catalyst is a porous bimetallic phosphide with a three-dimensional network structure and high-density electrochemical active sites.NiCoP@C exhibited favorable catalytic activity for the oxygen evolution reaction(OER)with overpotential of 280 mV at 10 mA·cm~(-2)and a Tafel slope of 77 mV·dec~(-1).Additionally,it exhibited remarkable durability during usage.Density functional theory(DFT)calculations revealed that by leveraging the distinctive structure of transition metal phosphide nanoparticles incorporated into a reticulated substrate,the NiCoP@C catalyst offered an increased number of active sites for OER catalysis,significantly enhancing its stability during practical applications.The present study broadens the utilization pathways of biomass to"turn waste into treasure,"aligning the development concept of green sustainable development.

Ultrafine Co nanoparticles confined in nitrogen-doped carbon toward two-electron oxygen reduction reaction for H_(2)O_(2) electrosynthesis in acidic media

Electrocatalytic production of hydrogen peroxide(H_(2)O_(2))by two-electron oxygen reduction reaction(2e^(-)ORR)under acidic condition has been considered to have great application value.Co nanoparticles(CoNPs)coupled with N-doped carbon are a class of potential electrocatalysts.The effective strategies to further enhance their performances are to improve the active sites and stability.Herein,the material containing ultrafine CoNPs confined in a nitrogen-doped carbon matrix(NC@CoNPs)was synthesized by pyrolyzing corresponding precursors,which was obtained through regulating the topological structure of ZIF-67/ZIF-8 with dopamine(DA).The DA self-polymerization process induced the formation of CoNPs with smaller sizes and formed polydopamine film decreased the detachment of CoNPs from the catalyst.High density of Co-N_(x) active sites and defective sites could be identified on NC@CoNPs,leading to high activity and H_(2)O_(2) selectivity,with an onset potential of 0.57 V(vs.RHE)and∼90%selectivity in a wide potential range.An on-site electrochemical removal of organic pollutant was achieved rapidly through an electro-Fenton process,demonstrating its great promise for on-site water treatment application.

基于混合电子/离子导体的无膜可穿戴汗液电解质传感器

利用可穿戴传感器对汗液电解质进行无创的实时监测可获得大量与健康相关的生理学信息.目前,可穿戴汗液传感器其电解质传感单元主要是基于固态离子选择电极(SC-ISEs).SC-ISEs包含2个功能传感层,即用于离子识别的离子选择性膜层(ISM)和信号转换的离子-电子转导层.然而,两层之间的水层效应、ISM层离子载体的生物毒性以及昂贵的成本导致SC-ISEs难以实际应用于可穿戴传感领域.本质上,这些挑战都源于ISM.基于此,本文提出了基于钨青铜混合电子/离子导体的无膜(ISM-free)离子传感器.该材料作为双功能传感层,无需传统的ISM,通过晶格实现离子识别,同时W^(6+/5+)氧化还原中心实现离子-电子的转导.相比于传统的离子载体,钨青铜表现出更为优异的性能.基于钨青铜构建的可穿戴离子传感器,实现了人体汗液NH_(4)^(+)和pH的监测.该工作提出了无膜固态离子传感的概念,强调了开发下一代无ISM可穿戴离子传感器的重要性.