Enhanced Pseudo-Capacitance Process in Nanoarchitectural Layered Double Hydroxide Nanoarrays Hollow Nanocages for Improved Capacitive Deionization Performance

Abstract

Layered double hydroxides (LDHs) are perceived as a hopeful capacitive deionization (CDI) faradic electrode for Cl– insertion due to its tunable composition, excellent anion exchange capacity, and fast redox activity. Nevertheless, the self-stacking and inferior electrical conductivity of the two-dimensional structure of LDH lead to unsatisfactory CDI performance. Herein, the three-dimensional (3D) hollow nanocage structure of CoNi-layered double hydroxide/carbon composites is well designed as a CDI anode by cation etching of the pre-carbonized ZIF-67 template. C/CoNi-LDH has a unique 3D hollow nanocage structure and abundant pore features, which can effectively suppress the self-stacking of LDH sheets and facilitate the transport of ions. Moreover, the introduced amorphous carbon layer can act as a conductive network. When employed as the CDI anode, C/CoNi-LDH exhibited a high Cl– removal capacity of 60.88 mg g–1 and a fast Cl– removal rate of 18.09 mg g–1 min–1 at 1.4 V in 1000 mg L–1 NaCl solution. The mechanism of the Cl– intercalation pseudo-capacitance reaction of C/CoNi-LDH is revealed by electrochemical kinetic analysis and ex situ characterization. This study provides vital guidance for the design of high-performance electrodes for CDI.

Electrodeposited CoNi-LDH nanosheets supported on halloysite nanotubes as a robust and highly efficient electrocatalyst for water oxidation

“…78 In the FT-IR spectrum of CoNi-LDH, the peaks at 535 and 640 cm −1 are associated with stretching vibrations of M–O and M–O–M (M = Fe, Co) bonds, respectively. 79 The observed peaks at 1384 and 1625 cm −1 are likely related to intercalated NO 3 − ions (N–O stretching mode) and the bending mode of water molecules, respectively. 79 The wide spectral band with a center at 3467 cm −1 represents a stretching vibration associated with the OH groups.…”

Polyoxometalate-Intercalated Tremella-Like CoNi-LDH Nanocomposites for Electrocatalytic Nitrite–Ammonia Conversion

“…Simultaneously, the released cobalt ions, together with Ni 2+ , co-precipitated with OH – to form CoNi-LDH nanosheets outside the perimeter of ZIF-67. Eventually, the original nanoarchitecture of ZIF-67 was completely destroyed, and the tremella-like CoNi-LDH was formed as a result. , Such a unique tremella-like morphology can effectively retard the self-stacking between CoNi-LDH layers, which further facilitates the subsequent intercalation of P 8 W 48 polyanions into their interlaminations . In the second step, the modified exfoliation assembly treatment , was implemented on the obtained CoNi-LDH and the KLiP 8 W 48 (Figure S2), after which tremella-like P 8 W 48 /CoNi-LDH was formed.…”

“…It is noteworthy that the position of the (003) diffraction peak moves from the original 10.79° of CoNi-LDH to a lower 2θ diffraction angle of 6.06°. According to Bragg’s equation (2 d sin θ = n λ, where d represents the layer spacing, n = 1, λ = 0.15406 nm), , the layer spacings of pristine NO 3 – intercalated CoNi-LDH and P 8 W 48 /CoNi-LDH can be calculated as 0.82 and 1.46 nm, respectively. The gallery height value of 0.98 nm can be obtained by subtracting the thickness of the host layer (0.48 nm) from the d -spacing value of P 8 W 48 /CoNi-LDH, which is almost equivalent to the theoretical diameter of the short axis of P 8 W 48 determined from the crystallographic data (1.0 nm) .…”

Porous NaTi2(PO4)3 Nanoparticles Encapsulated in Nitrogen-Doped Carbon Matrix for High-Performance Capacitive Deionization

“…Obviously, the electrode material is a key component in a CDI system. , In general, carbon-based electrode materials such as activated carbon (AC), , carbon nanotubes, carbon nanofibers, , and carbon aerogel are used as CDI electrode materials, and their desalination performance can be improved by increasing the specific surface area and developing a favorable porous structure. , However, the improvement of desalination by surface area and pore structure modification is limited. Besides, co-ion expulsion often occurs, leading to a significant decrease in charge efficiency and an increase in energy consumption.…”