Combating Li metal deposits in all-solid-state battery via the piezoelectric and ferroelectric effects.

All-solid-state Li-metal batteries (ASSLBs) are highly desirable, due to their inherent safety and high energy density; however, the irregular and uncontrolled growth of Li filaments is detrimental to interfacial stability and safety. Herein, we report on the incorporation of piezo-/ferroelectric BaTiO3 (BTO) nanofibers into solid electrolytes and determination of electric-field distribution due to BTO inclusion that effectively regulates the nucleation and growth of Li dendrites. Theoretical simulations predict that the piezoelectric effect of BTO embedded in solid electrolyte reduces the driving force of dendrite growth at high curvatures, while its ferroelectricity reduces the overpotential, which helps to regularize Li deposition and Li+ flux. Polarization reversal of soft solid electrolytes was identified, confirming a regular deposition and morphology alteration of Li. As expected, the ASSLBs operating with LiFePO4/Li and poly(ethylene oxide) (PEO)/garnet solid electrolyte containing 10% BTO additive showed a steady and long cycle life with a reversible capacity of 103.2 mAh g-1 over 500 cycles at 1 C. Furthermore, the comparable cyclability and flexibility of the scalable pouch cells prepared and the successful validation in the sulfide electrolytes, demonstrating its universal and promising application for the integration of Li metal anodes in solid-state batteries.

Ultrafast synthesis of hard carbon anodes for sodium-ion batteries.

Hard carbons (HCs) are a significantly promising anode material for alkali metal-ion batteries. However, long calcination time and much energy consumption are required for the traditional fabrication way, resulting in an obstacle for high-throughput synthesis and structure regulation of HCs. Herein, we report an emerging sintering method to rapidly fabricate HCs from different carbon precursors at an ultrafast heating rate (300 to 500 °C min-1) under one minute by a multifield-regulated spark plasma sintering (SPS) technology. HCs prepared via the SPS possess significantly fewer defects, lower porosity, and less oxygen content than those pyrolyzed in traditional sintering ways. The molecular dynamics simulations are employed to elucidate the mechanism of the remarkably accelerated pyrolysis from the quickly increased carbon sp2 content under the multifield effect. As a proof of concept, the SPS-derived HC exhibits an improved initial Coulombic efficiency (88.9%), a larger reversible capacity (299.4 mAh⋅g-1), and remarkably enhanced rate capacities (136.6 mAh⋅g-1 at 5 A⋅g-1) than anode materials derived from a traditional route for Na-ion batteries.

Semicrystalline IrOx with Abundant Boundaries for Overall Water Splitting.

Inorganic compounds with different crystalline and amorphous states may show distinct properties in catalytic applications. In this work, we control the crystallization level by fine thermal treatment and synthesize a semicrystalline IrOx material with the formation of abundant boundaries. Theoretical calculation reveals that the interfacial iridium with a high degree of unsaturation is highly active for the hydrogen evolution reaction compared to individual counterparts based on the optimal binding energy with hydrogen (H*). At the heat treatment temperature of 500 °C, the obtained IrOx-500 catalyst has dramatically promoted hydrogen evolution kinetics, endowing the iridium catalyst with a bifunctional activity for acidic overall water splitting with a total voltage of only 1.554 V at a current density of 10 mA cm-2. In light of the remarkable boundary-enhanced catalysis effects, the semicrystalline material should be further developed for other applications.

A General Synthesis of Mesoporous Hollow Carbon Spheres with Extraordinary Sodium Storage Kinetics by Engineering Solvation Structure.

Porous and hollow carbon materials have great superiority and prospects in electrochemical energy applications, especially for surface charge storage due to the high active surface. Herein, a general strategy is developed to synthesize mesoporous hollow carbon spheres (MHCS) with controllable texture and compositions by the synergistic effect of dopamine polymerization and metal catalysis (Cu, Bi, Zn). Mesoporous MHCS-Cu and MHCS-Bi are regular spheres, while mesoporous MHCS-Zn possesses an inward concave texture, and simultaneously has a very high surface area of 1675.5 m2 g-1 and lower oxygen content through the catalytic deoxygenation effect. MHCS-Zn displays an exceptional sodium storage kinetics and excellent long cycling life with 171.9 mAh g-1 after 2500 cycles at 5 A g-1 in compatible ether-based electrolytes. Such electrolyte enables enhanced solvated Na+ transport kinetics with appropriate electrostatic interactions at the surface of carbon anode as revealed by molecular dynamics simulations and molecular surface electrostatic potential calculations. Such an anode also displays basically constant capacity working at 0 °C, and still delivers 140 mAh g-1 at 3 A g-1 under -20 °C. Moreover, MHCS-Zn anode is coupled with Na3 V2 (PO4 )3 cathode to construct a hybrid capacitor, which exhibits a high energy density of 145 Wh Kg-1 at a very high power of 8009 W kg-1 .

Vitreum Etching-Assisted Fabrication of Porous Hollow Carbon Architectures for Enhanced Capacitive Sodium and Potassium-Ion Storage.

Carbonaceous materials exhibit promising application in electrochemical energy storage especially for hollow or porous structure due to the fascinating and outstanding properties. Although there has been achieved good progress, controllable synthesis of hollow or porous carbons with uniform morphology by a green and easy way is still a challenge. Herein, a new artful and green approach is designed to controllably prepare hollow porous carbon materials with the assistance of boron oxide vitreum under a relatively low temperature of 500 °C. The vitreous B2 O3 provides a flowing carbonization environment and acts as etching agent accompanying with boron doping. By this general strategy, hollow and porous carbon architectures with various morphology of spheres and hollow polyhedrons are successfully fabricated by metal organic framework (MOF) precursors. Furthermore, such hollow carbon materials exhibit considerably excellent Na+ /K+ storage properties through enhanced capacitive behavior due to due to the highly porous structure and large surface area. It is notable that hollow carbon spheres display nearly 90% initial Coulombic efficiency, outstanding rate capability with 130 mAh g-1 at 30 A g-1 and long cycling life for sodium ion storage.

Electrochemiluminescent competitive immunoassay for zearalenone based on the use of a mimotope peptide, Ru(II)(bpy)3-loaded NiFe2O4 nanotubes and TiO2 mesocrystals.

An ultrasensitive competitive-type electrochemiluminescence immunoassay for the mycotoxin zearalenone is described. The method is based on the use of (a) a mimotope peptide that was selected from a phage displayed peptide library and used to substitute ZEN for designing the competitive assay; (b) NiFe2O4 nanotubes with large specific surface area loaded with the ECL probe Ru(bpy)32+; and (c) poly(vinylpyrrolidone) (PVP)-assisted synthesis of TiO2 mesocrystals that acts as the sensing platform and support for antibody immobilization. Under the optimized conditions and at an ECL working potential of 1.1 V, a linear response is found for ZEN in the 0.1 to 1.0 × 10-5 ng·mL-1 concentration range with a detection limit as low as 3.3 fg·mL-1. Graphical abstract An ultrasensitive competitive-type electrochemiluminescence (ECL) immunosensor based on mimotope peptide was constructed for the detection of Zearalenone.

A Potentiometric Addressable Photoelectrochemical Biosensor for Sensitive Detection of Two Biomarkers.

It is a great challenge to fabricate multiplex and convenient photoelectrochemical biosensors for ultrasensitive determination of biomarkers. Herein, a fascinating potentiometric addressable photoelectrochemical biosensor was reported for double biomarkers' detection by varying the applied bias in the detection process. In this biosensor, the nanocomposite of cube anatase TiO2 mesocrystals and polyamidoamine dendrimers modified a dual disk electrode as an excellent photoelectrochemical sensing matrix. Subsequently, two important biomarkers in serum for prostate cancer, prostate-specific antigen and human interleukin-6, were immobilized onto the different disks of modified electrode via glutaraldehyde bridges. Then another two photosensitizers, graphitic-carbon-nitride-labeled and CS-AgI-labeled different antibodies, were self-assembled onto the electrode surface by a corresponding competitive immune recognition reaction. The change in photocurrent with the target antigen concentration at different critical voltages enables us to selectively and quantitatively determine targets. The results demonstrated that this potentiometric addressable photoelectrochemical biosensing strategy not only has great promise as a new point-of-care diagnostic tool for early detection of prostate cancer but also can be conveniently expanded to multiplex biosensing by simply change biomarkers. More importantly, this work provides an unambiguous operating guideline of multiplex photoelectrochemical immunoassay.

Enhanced photoelectrochemical activity of a hierarchical-ordered TiO2 mesocrystal and its sensing application on a carbon nanohorn support scaffold.

A ternary hybrid was developed through interaction between a hierarchical-ordered TiO2 and a thiol group that was obtained by in situ chemical polymerization of L-cysteine on the carbon nanohorn (CNH) superstructure modified electrode. Herein, unique-ordered TiO2 superstructures with quasi-octahedral shape that possess high crystallinity, high porosity, oriented subunit alignment, very large specific surface area, and superior photocatalytic activity were first introduced as a photosensitizer element in the photoelectrochemical determination. Additionally, the assembly of hierarchical-structured CNHs was used to provide an excellent electron-transport matrix to capture and transport an electron from excited anatase to the electrode rapidly, hampering the electron-hole recombination effectively, resulting in improved photoelectrochemical response and higher photocatalytic activity in the visible light region. Owing to the dependence of the photocurrent signal on the concentration of electron donor, 4-methylimidozal, which can act as a photogenerated hole scavenger, an exquisite photoelectrochemical sensor was successfully fabricated with a wide linear range from 1 × 10(-4) to 1 × 10(-10) M, and the detection limit was down to 30 pM. The low applied potential of 0.2 V was beneficial to the elimination of interference from other reductive species that coexisted in the real samples. More importantly, the mesocrystal was first introduced in the fabricating of a biosensor, which not only opens up a new avenue for biosensors manufactured based on mesocrystal materials but also provides beneficial lessons in the research fields ranging from solar cells to photocatalysis.

Understanding the growth and photoelectrochemical properties of mesocrystals and single crystals: a case of anatase TiO(2).

Anatase TiO2 mesocrystals and single crystals with dominant {101} facets were successfully synthesized without any additives using titanate nanowires as precursors under solvothermal and hydrothermal conditions, respectively. It is proposed that the oriented self-assembly process for the formation of TiO2 mesocrystals was controlled by the same thermodynamic principle as that of single crystals in this simple reaction system. Furthermore, the TiO2 mesocrystals were applied in photoelectrochemical (PEC) water splitting and demonstrated much enhanced photocurrent, almost 191% and 274% compared with that of TiO2 single crystals and commercial P25, respectively. Electrochemical impedance measurements under illumination revealed that the photocurrent increase was largely ascribed to the effective charge separation of electron-hole pairs and fast interfacial charge transfer. This could be attributed to the intrinsic characteristics of the mesostructured TiO2 composed of highly oriented nanocrystal subunits offering few grain boundaries, nanoporous nature and a short transport distance.

Unique ordered TiO(2) superstructures with tunable morphology and crystalline phase for improved lithium storage properties.

Unique ordered TiO(2) superstructures with tunable morphology and crystalline phase were successfully prepared by the use of different counterions. Dumbbell-shaped rutile TiO(2) and nanorod-like rutile mesocrystals constructed from ultrathin nanowires, and quasi-octahedral anatase TiO(2) mesocrystals built from tiny nanoparticle subunits were achieved. Interestingly, the obtained anatase mesocrystals have a fine microporous structure and a large surface area. The influence of the counterions in the reaction system is discussed and possible mechanisms responsible for the formation of the unique ordered TiO(2) superstructures with different morphologies and crystalline phases are also proposed based on a series of experimental results. The obtained TiO(2) superstructures were used as anode materials in lithium ion batteries, and exhibited higher capacity and improved rate performance; this is attributed to the intrinsic characteristics of the mesoscopic TiO(2) superstructures, which have a single-crystal-like and porous nature.

Strategies for Electrochemically Sustainable H2 Production in Acid.

Acidified water electrolysis with fast kinetics is widely regarded as a promising option for producing H2 . The main challenge of this technique is the difficulty in realizing sustainable H2 production (SHP) because of the poor stability of most electrode catalysts, especially on the anode side, under strongly acidic and highly polarized electrochemical environments, which leads to surface corrosion and performance degradation. Research efforts focused on tuning the atomic/nano structures of catalysts have been made to address this stability issue, with only limited effectiveness because of inevitable catalyst degradation. A systems approach considering reaction types and system configurations/operations may provide innovative viewpoints and strategies for SHP, although these aspects have been overlooked thus far. This review provides an overview of acidified water electrolysis for systematic investigations of these aspects to achieve SHP. First, the fundamental principles of SHP are discussed. Then, recent advances on design of stable electrode materials are examined, and several new strategies for SHP are proposed, including fabrication of symmetrical heterogeneous electrolysis system and fluid homogeneous electrolysis system, as well as decoupling/hybrid-governed sustainability. Finally, remaining challenges and corresponding opportunities are outlined to stimulate endeavors toward the development of advanced acidified water electrolysis techniques for SHP.

Swallowing Lithium Dendrites in All-Solid-State Battery by Lithiation with Silicon Nanoparticles.

Eliminating the uncontrolled growth of Li dendrite inside solid electrolytes is a critical tactic for the performance improvement of all-solid-state Li batteries (ASSLBs). Herein, a strategy to swallow and anchor Li dendrites by filling Si nanoparticles into the solid electrolytes by the lithiation effect with Li dendrites is proposed. It is found that Si nanoparticles can lithiate with the adjacent Li dendrites which have a strong electron transport ability. Such effect can inhibit the formation of Li dendrites at the interface of Li anode, and also swallow the tip Li inside the solid electrolytes, and thus inhibiting its longitudinal growth and avoiding the solid electrolyte puncturing. As a proof of concept, a novel sandwich-structure solid electrolyte of Li6.7 La3 Zr2 Al0.1 O12 (LLZA)-PEO/Si-PEO electrolyte/ (LLZA)-PEO with asymmetrical structure is first constructed and demonstrated stable Li plating/stripping over 1800 h and remarkably improved cycling stability in Li/LiFePO4 cells with a reversible capacity of 111.9 mAh g-1 at 1 C after 150 cycles. The proof of lithiation of Si-PEO electrolyte in the interlayer is also verified. Furthermore, the pouch cell thus prepared exhibits comparable cyclic stability and is allowable for folding and cutting, suggesting its promising application in ASSLBs by this simple and efficient strategy.

A multiple mixed TiO2 mesocrystal junction based PEC-colorimetric immunoassay for specific recognition of lipolysis stimulated lipoprotein receptor.

A flexible two-step photoelectrochemical (PEC)-colorimetric immunoassay was proposed for ultrasensitive detection of lipolysis stimulated lipoprotein receptor (LSR) which is found to be closely related to ovarian cancer (OC). In this paper, the Cu nanoclusters (CuNCs) enhanced multiple mixed TiO2 mesocrystals junction (MMMJ) was fabricated via effective combination of multiple different phases TiO2 mesocrystals (Anatase and Rutile) layers and used as a sensing platform. The strong interaction between different phases layers caused multiple amplification of signal and introduction of Cu NCs further improve PEC properties and catalytic activity to hydrogen peroxide (H2O2) what can catalyze lecuo-methylene blue (lecuo-MB) from colorless to blue. As antibody and target antigen captured onto the MMMJ in turn, both PEC properties and catalytic activities were inhibited, leading to decreased photocurrent responses and multiply vivid color variations in lecuo-MB functionalized colorimetric films. Thus, a versatile dual-modal sensing system was developed just by utilizing enhanced MMMJ as a photoelectrode and lecuo-MB as a color change reporter molecule for PEC and colorimetric monitoring of target. Combing all of these advantages, the designed dual-modal immunoassay considerately reduced false positive or negative results during the measurement, and the unique approach for MMMJ construction may also provide a valuable guidance for designing other mixed phase junctions with superior PEC performance.

Structural evolution from layered Na2Ti3O7 to Na2Ti6O13 nanowires enabling a highly reversible anode for Mg-ion batteries.

The development of suitable host materials for the reversible storage of divalent ions such as Mg2+ is still a big challenge and its progress to date has been slow compared to that of monovalent Li+ or Na+. Herein, we present the study of layered sodium trititanate (Na2Ti3O7) and sodium hexatitanate (Na2Ti6O13) nanowires as anode materials for rechargeable Mg-ion batteries. It is found for the first time that the structural evolution from layered Na2Ti3O7 to Na2Ti6O13 with a more condensate three-dimensional microporous structure enables remarkably enhanced Mg-ion storage performance. The Na2Ti6O13 electrode can achieve a large initial discharge and charge capacity of 165.8 and 147.7 mA h g-1 at 10 mA g-1 with a record high initial coulombic efficiency up to 89.1%. Ex situ XRD, Raman measurements and EDX mapping were used to investigate the electrochemical reaction mechanism. It is suggested that the irreversible structure change and the formation of insoluble NaCl with high yield and large particles when Na+ is replaced by inserted Mg2+ for the Na2Ti3O7 electrode could be ascribed to the rapid decline in capacity. By contrast, the Na2Ti6O13 electrode exhibits good structure stability during the Mg-ion insertion/extraction process, leading to good rate performance and cycling stability.

A mimotope peptide-based dual-signal readout competitive enzyme-linked immunoassay for non-toxic detection of zearalenone.

In this study, a mimotope peptide-based non-toxic photoelectrochemical (PEC) competitive enzyme-linked immunoassay (ELISA) was established for ultrasensitive detection of zearalenone (ZEN) with dual-signal readout. Using the phage display technique (PDT), a mimotope peptide of ZEN could be harvested by selecting a peptide from a phage-display peptide library, which avoided using mycotoxin itself and minimized potential damage to operators. The tyramine-modified rutile TiO2 mesocrystals (Tyr-RMC) with outstanding PEC properties were utilized as reporter units to label the mimotope peptide. The fabricated peptide@Tyr-RMC probe could anchor on the antibody-modified electrode via competitive immune recognition of free target ZEN. When subjected to catalysis of HRP-H2O2, the Tyr-RMC composite was deposited at the enzyme reaction site, causing rolling circle extension of the reporter unit chains. By merit of the brilliant signal amplification effect of tyramine signal amplification (TSA), dramatically enhanced photocurrent response and enormously increased electrochemical impedance could be determined. Combining all of these advantages, the developed dual-signal readout non-toxicity immunoassay could effectively decrease environmental interference. Also, the designed dual-signal readout biosensor demonstrated a wide linear range between 10-6 and 1 ng mL-1 with a low detection limit of 1 × 10-6 ng mL-1, which provides a valuable reference for developing highly efficient, secure and sensitive detection methods and indicates promising applicability in food testing.

Dual-readout immunosensor constructed based on brilliant photoelectrochemical and photothermal effect of polymer dots for sensitive detection of sialic acid.

A delicate dual-readout immunosensor based on tetraphenylporphyrin-polymer dots (TPP-Pdots) with brilliant photoelectrochemical and photothermal performance was first successfully fabricated for the ultrasensitive detection of sialic acid (SA). Herein, TPP-Pdots with good biocompatibility, extraordinary light-harvesting ability and excellent photothermal conversion efficiency was used to capture SA antibody as dual-functional bioprobe for generating photocurrent and temperature signal. Furthermore, the large surface and morphology-mediated of rutile-TiO2 (R-TiO2) was beneficial to load amounts of TPP-Pdots for improved PEC signal and photothermal signal. Importantly, the temperature readout resulted from the variation of target concentration could be easily obtained by a universal thermometer which was time-saving and cost-saving. Under the optimized experimental conditions, the photocurrent densities and temperature changes proportionally increased with the increasing of SA concentrations from 3.5 × 10-5 ng/mL to 35 ng/mL (R = 0.996). Impressively, the dual-readout approach proposed here not only featured with good accuracy and high sensitivity for SA detection, but also paved the way for the development of a dual-readout immunoassay based on PEC biosensor.

In Situ Observation of the Insulator-To-Metal Transition and Nonequilibrium Phase Transition for Li1-xCoO2 Films with Preferred (003) Orientation Nanorods.

It is notoriously difficult to distinguish the stoichiometric LiCoO2 (LCO) with a O3-I structure from its lithium defective O3-II phase because of their similar crystal symmetry. Interestingly, moreover, the O3-II phase shows metallic conductivity, whereas the O3-I phase is an electronic insulator. How to effectively reveal the intrinsic mechanism of the conductivity difference and nonequilibrium phase transition induced by the lithium deintercalation is of vital importance for its practical application and development. Based on the developed technology of in situ peak force tunneling atomic force microscopy (PF-TUNA) in liquids, the phase transition from O3-I to O3-II and consequent insulator-to-metal transition of LCO thin-film electrodes with preferred (003) orientation nanorods designed and prepared via magnetron sputtering were observed under an organic electrolyte for the first time in this work. Then, studying the post-mortem LCO thin-film electrode by using ex situ time-dependent XRD and conductive atomic force microscopy, we find the phase relaxation of LCO electrodes after the nonequilibrium deintercalation, further proving the differences of the electronic conductivity and work function between the O3-I and O3-II phases. Moreover, X-ray absorption spectroscopy results indicate that the oxidation of Co ions and the increasing of O 2p-Co 3d hybridization in the O3-II phase lead to electrical conductivity improvement in Li1-xCoO2. Simultaneously, it is found that the nonequilibrium deintercalation at a high charging rate can result in phase-transition hysteresis and the O3-I/O3-II coexistence at the charging end, which is explained well by an ionic blockade model with an antiphase boundary. At last, this work strongly suggests that PF-TUNA can be used to reveal the unconventional phenomena on the solid/liquid interfaces.

A bifunctional reagent regulated ratiometric electrochemiluminescence biosensor constructed on surfactant-assisted synthesis of TiO2 mesocrystals for the sensing of deoxynivalenol.

Herein, a delicate bifunctional reagent regulated ratiometric electrochemiluminescence (ECL) biosensor was developed for the detection of deoxynivalenol (DON) by virtue of the ratio of two ECL signals from Luminol and tris(4,4'-dicarboxylicacid-2,2'-bipyridyl) ruthenium(II) dichloride (Ru(dcbpy)32+). Initially, surfactant-assisted synthesis of TiO2 mesocrystals dispersing in Nafion and ionic liquid (IL) complex film held great promises in loading Ru(dcbpy)32+ and amplifying the ECL signal. Additionally, helical carbon nanotube (HCNTs) with superior specific area and good conductivity emerging as a scaffold not only realized the high fixing of Luminol, ferrocenecarboxylic acid (FCA) and secondary antibody (Ab2), but accelerated the electron transfer. It's noteworthy that FCA was first utilized as a bifunctional reagent to regulate the ratiometric ECL sensing mode on account of the influences in enhancing the ECL response of Luminol and quenching the ECL emission of Ru(dcbpy)32+. On the basis of the sandwich-type immunoreactions between Ab1, DON and Ab2, an accurate and sensitive ratiometric ECL immunosensor was established for the detection of DON in a wide range from 0.05 pg/mL to 5 ng/mL with the detection limit of 1.67 × 10-2 pg/mL.

Rational Design and General Synthesis of S-Doped Hard Carbon with Tunable Doping Sites toward Excellent Na-Ion Storage Performance.

Heteroatom-doping is a promising strategy to tuning the microstructure of carbon material toward improved electrochemical storage performance. However, it is a big challenge to control the doping sites for heteroatom-doping and the rational design of doping is urgently needed. Herein, S doping sites and the influence of interlayer spacing for two kinds of hard carbon, perfect structure and vacancy defect structure, are explored by the first-principles method. S prefers doping in the interlayer for the former with interlayer distance of 3.997 Å, while S is doped on the carbon layer for the latter with interlayer distance of 3.695 Å. More importantly, one step molten salts method is developed as a universal synthetic strategy to fabricate hard carbon with tunable microstructure. It is demonstrated by the experimental results that S-doping hard carbon with fewer pores exhibits a larger interlayer spacing than that of porous carbon, agreeing well with the theoretical prediction. Furthermore, the S-doping carbon with larger interlayer distance and fewer pores exhibits remarkably large reversible capacity, excellent rate performance, and long-term cycling stability for Na-ion storage. A stable and reversible capacity of ≈200 mAh g-1 is steadily kept even after 4000 cycles at 1 A g-1 .

Synthesis of Mesoporous Co2+-Doped TiO2 Nanodisks Derived from Metal Organic Frameworks with Improved Sodium Storage Performance.

TiO2 is a most promising anode candidate for rechargeable Na-ion batteries (NIBs) because of its appropriate working voltage, low cost, and superior structural stability during chage/discharge process. Nevertheless, it suffers from intrinsically low electrical conductivity. Herein, we report an in situ synthesis of Co2+-doped TiO2 through the thermal treatment of metal organic frameworks precursors of MIL-125(Ti)-Co as a superior anode material for NIBs. The Co2+-doped TiO2 possesses uniform nanodisk morphology, a large surface area and mesoporous structure with narrow pore distribution. The reversible capacity, Coulombic efficiency (CE) and rate capability can be improved by Co2+ doping in mesoporous TiO2 anode. Co2+-doped mesoporous TiO2 nanodisks exhibited a high reversible capacity of 232 mAhg-1 at 0.1 Ag1-, good rate capability and cycling stability with a stable capacity of about 140 mAhg-1 at 0.5 Ag1- after 500 cycles. The enhanced Na-ion storage performance could be due to the increased electrical conductivity revealed by Kelvin probe force microscopy measurements.