Kinetically and Thermodynamically Favorable Ni–Al Layered Double Hydroxide/Ni-Doped Zn_0.5Cd_0.5S S-Scheme Heterojunction Triggering Photocatalytic H₂ Evolution

Abstract

Layered double hydroxide (LDH)-based photocatalysts have attracted more attention in photocatalysis due to their low cost, wide band gaps, and adjustable photocatalytic active sites; however, their low photogenerated carrier separation efficiency limits their photocatalytic efficiency. Herein, a NiAl-LDH/Ni-doped Zn0.5Cd0.5S (LDH/Ni-ZCS) S-scheme heterojunction is rationally designed and constructed from kinetically and thermodynamically favorable angles. The 15% LDH/1% Ni-ZCS displays comparable photocatalytic hydrogen evolution (PHE) activity with a rate of 6584.0 μmol g–1 h–1, which exceeds by ∼6.14- and ∼1.73-fold those of ZCS and 1% Ni-ZCS, respectively, and outperforms most of the previously reported LDH-based and metal sulfide-based photocatalysts. In addition, the apparent quantum yield of 15% LDH/1% Ni-ZCS reaches 12.1% at 420 nm. In situ X-ray photoelectron spectroscopy, photodeposition, and theoretical calculation reveal the specific transfer path of photogenerated carriers. On this basis, we propose the possible photocatalytic mechanism. The fabrication of the S-scheme heterojunction not only accelerates the separation of photogenerated carriers but also decreases the activation energy of H2 evolution and improves the redox capacity. Moreover, there are huge amounts of hydroxyl groups distributed on the surface of photocatalysts, which is highly polar and easy to combine with H2O with a large dielectric constant to form a hydrogen bond, which can further accelerate PHE.

Challenges in Photocatalytic Carbon Dioxide Reduction

“…Based on this issue, researchers has reported many state-of-art spectroscopic characterizations including in situ X-ray photoelectron spectroscopy (XPS), − Femto-second transient absorption spectra (fs-TAS), Kelvin probe force microscopy (photo-KPFM), etc. and theoretical calculations , to illustrate the charge transfer mechanism . For example, the peaks (Zn 2p and Cd 3d) in C 60 -mediated NH 2 -MIL-125­(Ti)/Zn 0.5 Cd 0.5 S (NMTCZ-45) move to greater binding energy without light irradiation, suggesting that Zn 0.5 Cd 0.5 S (ZCS) in NMTCZ-45 is an electron donors.…”

Lattice capacity-dependent activity for CO2 methanation: crafting Ni/CeO2 catalysts with outstanding performance at low temperatures

“…Among the various Ni-based catalysts, 19–25 CeO 2 support has been widely employed due to its abundant oxygen vacancies and robust oxygen storage capacity, 18,26–30 which holds the potential to enhance the low-temperature reaction activity. 11,18,21,29 In the pursuit of preparing high and low temperature-active catalysts, strategies such as hydrogen-rich stream, 23 modifying with Ce, 24 and constructing interfaces 25 have shown promising results.…”

Hierarchical (CdZnCuCoFe)S1.25/ZnIn2S4 Heterojunction for Photocatalytic CO2 Reduction: Insights into S-Scheme Charge Transfer Pathways in Type-I Band Alignment

“…Among various semiconductors, ZnIn 2 S 4 (ZIS) has gained prominence owing to its favorable band structure and visible light absorption for CO 2 photoreduction reactions. , However, like the majority of unitary photocatalysts, the photocatalytic efficiency of ZIS is considerably below the level required for practical applications. This is primarily due to its high electron–hole recombination rate. , In principle, hybridizing ZIS with another semiconductor with suitable band structure provides the most attractive strategy to maximize its photocatalytic activity.…”