Modulation of Trivalent/Tetravalent Metallic Elements in Ni-Based Layered Double Hydroxides for Photocatalytic CO₂ Reduction

Abstract

Herein, by modulating trivalent/tetravalent metallic elements, NiMLDHs (M = Al, Co, Fe, Mn, and Ti) were successfully prepared and evaluated in photocatalytic CO2 reduction reaction (PCRR). Photocatalytic results declared that the electronic yields followed the order of NiTiLDH > NiCoLDH > NiFeLDH > NiMnLDH > NiAlLDH. Multiple characterizations affirmed that the introduction of various trivalent/tetravalent metallic elements could visibly affect the three critical aspects: (i) light harvesting; (ii) charge separation and transfer; and (iii) surface reactions, thus governing PCRR performance. Importantly, an in-depth mechanistic investigation was conducted by in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) experiments. These layered double hydroxides (LDHs) exhibited different adsorption/activation behaviors toward CO2 molecule: NiAlLDH primarily converted CO2 into b-CO3 2– species; NiCoLDH, NiFeLDH, and NiMnLDH could induce c-CO3 2– intermediate; NiTiLDH could generate a higher proportion of •CO2 – species, which was an important intermediate to produce CO. More favorable carries separation and adsorption/activation process was presented upon NiTiLDH, thus more markedly enhancing photoactivity.

Metal Vacancies in CoAl-Layered Double Hydroxide Nanosheets Enabling Boosted Visible Light Driven CO2 Photoreduction

“…As shown in Figure S16, with irradiation time going from 0 to 30 min, several IR peaks gradually increased. The broad peaks at 1469 and 1704 cm –1 were assigned to HCO 3 * and CO 3 2– , respectively. , And the peaks at 1369 and 1573 cm –1 can be ascribed to COOH*. , COOH* was the common intermediate in the photoreduction of CO 2 and was generally transformed into CO* subsequently and produce CO finally . Therefore, the possible CO 2 photoreduction to CO process was proposed according to previous reports and experimental results. , First, H 2 O was split to produce active hydrogen species (H*) by the reduction reaction, then H* combined with adsorbed CO 2 to form COOH* intermediate and converted into CO ultimately.…”

“…57,58 And the peaks at 1369 and 1573 cm −1 can be ascribed to COOH*. 18,57 COOH* was the common intermediate in the photoreduction of CO 2 and was generally transformed into CO* subsequently and produce CO finally. 59 Therefore, the possible CO 2 photoreduction to CO process was proposed according to previous reports and experimental results.…”

“…The broad peaks at 1469 and 1704 cm −1 were assigned to HCO 3 * and CO 3 2− , respectively. 57,58 And the peaks at 1369 and 1573 cm −1 can be ascribed to COOH*. 18,57 COOH* was the common intermediate in the photoreduction of CO 2 and was generally transformed into CO* subsequently and produce CO finally.…”

A novel S-scheme heterojunction constructed by Ti-based hydrotalcite decorating MOFs for boosting CO2-to-CO photoreduction and mechanism insights

“…38 Considering that the aluminium element has d 0 classification and thereby demonstrates less promotion in CO 2 RR, the substitution of Al with Co, Fe, Mn and Ti elements has been pursued, where NiTiLDH offered the most available active sites for bonding and activating CO 2 . 39 More importantly, NiTiLDH possessed a high reduction potential, thereby serving as a desired platform for exploring high-efficiency heterojunction photocatalysts.…”

Oxygen Vacancy Induced Atom-Level Interface in Z-Scheme SnO2/SnNb2O6 Heterojunctions for Robust Solar-Driven CO2 Conversion

“…Simulating natural photosynthesis, which directly converts carbon dioxide (CO 2 ) into valuable hydrocarbon fuels using sunlight at room temperature and atmospheric pressure, provides promising technology to support renewable carbon fixation and energy storage. , So far, numerous photocatalysts, such as NaNbO 3 , ZnGa 2 O 4 , CdS, TiO 2 , , g-C 3 N 4 , , metal–organic frameworks, , zeolite molecular sieves, and layered double hydroxides, have been developed for CO 2 reduction. However, the practical implementation of existing photocatalysts is severely restricted by the low CO 2 conversion efficiency and poor stability due to the low light utilization, rapid recombination of photoinduced carriers, sluggish kinetics of electron transfer, and high energy barriers for CO 2 activation .…”