Synthesis of Water-Dispersible Single-Layer CoAl-Carbonate Layered Double Hydroxide

Abstract

Despite extensive study on single-layer layered double hydroxides (SL-LDHs) with NO counterions, SL-LDHs with CO counterions (CO SL-LDHs) have never been prepared before. Herein, a CoAl-CO SL-LDH which stays stable in water and powdery state is first synthesized using ethylene glycol as a reaction medium. The SL-LDH, with thickness of ∼0.85 nm, is composed of one Co(Al)O layer sandwiched between two CO layers. The SL-LDH powder shows high specific surface area (∼289 m/g) and excellent electrocatalytic oxygen evolution efficiency. This work provides the first simple way to prepare CO SL-LDHs and will open an avenue for synthesizing other SL-LDHs.

Superhydrophilic Graphdiyne Accelerates Interfacial Mass/Electron Transportation to Boost Electrocatalytic and Photoelectrocatalytic Water Oxidation Activity

“…At the overpotential of 300 mV, the catalytic current density could reach 24.8 mA cm −2 . Based on the amount of catalysts on superhydrophilic GDY measured by ICP‐MS (6.35 µg cm −2 ), the TOF was calculated to be ≈0.60 s −1 at the overpotential of 300 mV, which is the best record in both CoAl‐based and GDY‐based LDH electrocatalysts, even comparable to the best performance of LDH‐based electrocatalysts for oxygen evolution (Table S1, Supporting Information). As to the hydrophobic CoAl‐LDH/GDY, it required ≈360 mV to reach 10 mA cm −2 current density (Figure b) and the amount of catalysts adsorbed on hydrophobic GDY electrode was ≈4.97 µg cm −2 , corresponding to a TOF of ≈0.14 s −1 at η = 300 mV, which are poorer than those of superhydrophilic CoAl‐LDH/GDY electrode.…”

“…Preparation of Ultrathin CoAl‐LDH (CO 3 2− ) Nanosheets : Ultrathin CoAl‐LDH (CO 3 2− ) nanosheets were prepared as follows . Typically, 0.8 mmol of Co(NO 3 ) 2 ·6H 2 O, 0.4 mmol of Al(NO 3 ) 3 ·9H 2 O, and 2.8 mmol of urea were put into a 100 mL Teflonlined autoclave containing 80 mL of ethylene glycol, and heated at 100 °C for 24 h. After cooled to room temperature, the suspension was centrifuged to get the paste sample and washed by ethanol for three times.…”

“…Compared with conventional oxidant‐treated manner, plasma can avoid destroying the substrate, which is very important to the fabrication of devices. As a representative catalyst, ultrathin CoAl (CO 3 2− ) layered double hydroxides (LDHs) nanosheets were assembled on superhydrophilic GDY for oxygen evolution reaction (OER), the bottleneck of water splitting ( Scheme ) . To our delight, the superhydrophilic CoAl‐LDH/GDY showed excellent OER activity with an overpotential of ≈258 mV to reach 10 mA cm −2 , much better than that of hydrophobic CoAl‐LDH/GDY (≈360 mV) under the same condition.…”

“…To our delight, the superhydrophilic CoAl‐LDH/GDY showed excellent OER activity with an overpotential of ≈258 mV to reach 10 mA cm −2 , much better than that of hydrophobic CoAl‐LDH/GDY (≈360 mV) under the same condition. The turnover frequency (TOF) on the basis of Co was determined as ≈0.60 s −1 at η = 300 mV, which is the best value in both CoAl‐based and GDY‐based LDH electrocatalysts . Density functional theory (DFT) calculations revealed that superhydrophilic GDY exhibited a more negative charge density and could attract H 2 O molecules closer to catalysts, thus facilitating interfacial mass/electron transportation efficiently (see below).…”

Graphdiyne: A Rising Star of Electrocatalyst Support for Energy Conversion

“…[ 84 ] The obtained CoAl‐LDH/HGDY displayed unprecedented catalytic performance with a low overpotential of about 258 mV to attain 10 mA cm −2 , which was the best record for OER among all CoAl‐based and GDY‐based LDH electrocatalysts. [ 85,86 ] The unprecedented catalytic performance was attributed to the electrostatic interaction between HGDY (negative charge density) and CoAl‐LDH (positive charge density), which was favorable for catalyst combination. The high conductivity of HGDY accelerated the charge transfer and the superhydrophilic HGDY made catalyst have an intimate contact with electrolyte, thereby improving interfacial mass transport and electron transfer.…”