Elaborately Designed Hierarchical Heterostructures Consisting of Carbon‐Coated TiO₂(B) Nanosheets Decorated with Fe₃O₄ Nanoparticles for Remarkable Synergy in High‐Rate Lithium Storage

Abstract

and transition metal oxides (TMOs) [13][14][15][16] have recently been explored as promising anode candidates.TiO 2 , among other TMOs, is particularly attractive owing to its fascinating features including high structural stability, long cycle life, low cost, and high safety. [17][18][19][20][21] TiO 2 (B), as an unusual polymorph (bronze-phase) of TiO 2 , is found to have an open-channel structure and display a pseudo-capacitive behavior, thus enabling easier Li + diffusion and faster chargingdischarging capabilities. [ 22 ] Its theoretical capacity (335 mA h g −1 ) therefore significantly surpasses that (≈170 mA h g −1 ) of anatase or rutile TiO 2 , and is comparable to that (372 mA h g −1 ) of graphitic carbons. In consequence, various TiO 2 (B) nanostructures in the form of, e.g., nanoparticles, [23][24][25] nanorods, [ 26,27 ] nanowires, [28][29][30][31] nanotubes, [32][33][34][35][36] or nanosheets, [ 37,38 ] have been intensively studied as LIB anodes.It is worth noting, however, that the poor intrinsic conductivity of TiO 2 (B) inevitably sets obstacles for its applications as a high-power anode material. In this context, various carbonaceous materials, e.g., activated carbon fabrics, [ 39 ] carbon coatings, [ 40 ] carbon nanotubes, [ 41 ] or graphene nanosheets, [42][43][44][45] are introduced as conductive additives to ease the electron transport, thereby improving the cycle performances of TiO 2 (B) at high rates. Despite this progress, the reversible capacity of TiO 2 (B) is still insuffi cient, especially when compared to other TMOs, such as Fe 2 O 3 , [46][47][48][49][50] SnO 2 , [51][52][53][54] Co 3 O 4 , [ 55 ] and MnO 2 , [ 56 ] all of which boast of their much higher theoretical capacities (800−1200 mA h g −1 ) than TiO 2 (B).In this work, we expect to address the conductivity and capacity defi ciencies of TiO 2 (B) through a smart morphological and compositional design, aiming to achieve excellent reversible capacities and rate capabilities at the same time. Here we report elaborately designed hierarchical heterostructures, consisting of carbon-coated TiO 2 (B) nanosheets decorated with Fe 3 O 4 nanoparticles, based on a one-step self-assembly strategy through van der Waals interactions. [ 57 ] We stress that compared to other hybridization approaches based on hydrothermal synthesis, [46][47][48][50][51][52][53]55,56 ] atomic layer deposition, [ 49 ] and thermal pyrolysis, [ 54 ] our one-step self-assembly strategy is really facile and energy-effi cient, since it does not require harsh

Hierarchy Design in Metal Oxides as Anodes for Advanced Lithium‐Ion Batteries

“…Combining such nanostrucrtured materials with carbon‐based systems is also an attractive strategy to improve the diffusion capability of Li + /e − in TiO 2 . For instance, Jiang et al combined anatase/TiO 2 ‐B with conductive carbon and reduced graphene oxide (rGO), to form a hierarchically porous carbon‐coated mixed‐phase TiO 2 nanosheet/rGO composite (TiO 2 @C/rGO) through a one‐pot solvothermal process .…”

Boosting High‐Rate Lithium Storage of V2O5 Nanowires by Self‐Assembly on N‐Doped Graphene Nanosheets

“…It is well known that the crystallinity of nanostructured transition metal oxides can be further improved through heat treatment, which usually results in optimized electrochemical performance . To screen the proper conditions, neat V 2 O 5 nanowires were subjected to heat treatment at different temperatures (200, 300, and 400 °C).…”

“…Previously we have successfully assembled small entities (i.e. symmetric and asymmetric nanoparticles) on various two-dimensional matrices, including graphene, [37] transition metal dichalcogenides, [38,39] transition metal oxides, [40,41] and hexagonal BN. [42] Interestingly,i nt his work we found that larger entities such as V 2 O 5 nanowires can also be assembled on the Ndopedg raphene nanosheets in ad ense and uniform way,a s showni nF igure 2a and b.…”

“…It is well known that the crystallinity of nanostructured transition metal oxidesc an be furtheri mprovedt hroughh eat treatment, which usually resultsi no ptimized electrochemical performance. [40] To screen the proper conditions, neat V 2 O 5 nanowires were subjected to heatt reatment at different temperatures (200, 300, and 400 8C). The XRD patterns in Figure S6 show that heat treatment at 200 8Ci si nsufficient for crystal transformation,a nd all peaks have largeh alf-peak widths characteristic of low crystallinity.O nly when the temperature is raised to 300 8Co ra bove can sharp peaks agreeingw ellw ith orthorhombic V 2 O 5 be observed (JCPDS card No.…”

Carbon‐Nanoplated CoS@TiO2 Nanofibrous Membrane: An Interface‐Engineered Heterojunction for High‐Efficiency Electrocatalytic Nitrogen Reduction

“…Figure e presents the C 1s spectrum, in which the intense peak at 284.8 eV belongs to the C−C bonds originating from the carbonization of polydopamine. The tiny peak at 286.5 eV refers to the C−O bonds, which is consistent with the O 1s spectrum.…”