Alkaline-Etched NiMgAl Trimetallic Oxide-Supported KMoS-Based Catalysts for Boosting Higher Alcohol Selectivity in CO Hydrogenation

Topologically Porous Heterostructures for Photo/Photothermal Catalysis of Clean Energy Conversion

As a straightforward way to fix solar energy, photo/photothermal catalysis with semiconductor provides a promising way to settle the energy shortage and environmental crisis in many fields, especially in clean energy conversion. Topologically porous heterostructures (TPHs), featured with well-defined pores and mainly composed by the derivatives of some precursors with specific morphology, are a major part of hierarchical materials in photo/photothermal catalysis and provide a versatile platform to construct efficient photocatalysts for their enhanced light absorption, accelerated charges transfer, improved stability, and promoted mass transportation. Therefore, a comprehensive and timely review on the advantages and recent applications of the TPHs is of great importance to forecast the potential applications and research trend in the future. This review initially demonstrates the advantages of TPHs in photo/photothermal catalysis. Then the universal classifications and design strategies of TPHs are emphasized. Besides, the applications and mechanisms of photo/photothermal catalysis in hydrogen evolution from water splitting and CO_x hydrogenation over TPHs are carefully reviewed and highlighted. Finally, the challenges and perspectives of TPHs in photo/photothermal catalysis are also critically discussed.

Atomic Scale Optimization Strategy of Al-Based Layered Double Hydroxide for Alkali Stability and Supercapacitors

The pseudocapacitor material is easily decomposed when immersed in alkaline solution for a long time. Hence, it is necessary to find a strategy to improve the alkali stability of pseudocapacitor materials. In addition, the relationship between alkali stability and electrochemical performance is still unclear. In this work, a series of Al-based LDH (Layered double hydroxide) and derived Ni/Co-based sulfides are prepared, and corresponding alkali stability and electrochemical performance are analyzed. The alkali stability of CoAl LDH is so poor and can be improved effectively by doping of Ni. Ni₁Co₂S₄ and Ni₂Co₁Al LDH exhibit an outstanding alkali stability, and Ni₂Co₁S₄ exhibits an extremely poor alkali stability. The variable valence state of Co element and the solubility of Al in alkali solution are the fundamental reasons for the poor alkali stability of CoAl LDH and Ni₂Co₁S₄. Ni₂Co₁S₄ showed an outstanding electrochemical performance in a three-electrode system, which is better than that of Ni₁Co₂S₄, indicating that there is no direct correlation between alkali stability and electrochemical properties. Sulfidation improved the electrical conductivity and electrochemical activity of electrode materials, whereas alkali etching suppressed the occurrence of the electrochemical reaction. Overall, this work provides a clear perspective to understand the relationship between alkali stability and electrochemical properties.

Activation of the MoS2 Basal Plane to Enhance CO Hydrogenation to Methane Activity Through Increasing S Vacancies

The active site of MoS₂ is usually located at the edge of crystalline MoS₂, which has a lower proportion than that from the basal plane, limiting the hydrogenation activity. Therefore, activating the basal plane of MoS₂ is expected to greatly enhance the hydrogenation activity. Herein, we prepared a series of MoS₂ catalysts by acidolysis of ammonium tetrathiomolybdate and subsequently pyrolyzing at high temperature with different atmospheres. Through analysis, we found that the prepared MoS₂ catalysts were curved, which was different from commercial MoS₂. Through X-ray diffraction, transmission electron microscopy, and Raman and X-ray photoelectron spectroscopy characterization, it was found that the MoS₂ catalyst pyrolyzed under a N₂ atmosphere had a larger number of S-vacancies than the MoS₂ catalysts under a H₂ atmosphere. In addition, temperature-programmed reduction results showed that the Mo-S bond energy was decreased with the increasing content of S-vacancies, which might be related to bending. Sulfur-resistant methanation results indicated that the curved MoS₂ exhibited increased CO conversion with the increasing S vacancies. Furthermore, density functional theory calculation was used to simulate the generation of S vacancy and numbers of S vacancies. It was found that with the generation of S vacancy, three unsaturated coordination Mo atoms were exposed around one S vacancy and became new active sites, resulting in enhanced activity. What is more, the higher methanation activity was attributed not only from more S vacancies but also from the decreased activation energy for CO hydrogenation activation.

CuCo alloy nanonets derived from CuCo2O4 spinel oxides for higher alcohols synthesis from syngas

Porous CuCo alloy nanonets were used as superior catalysts for higher alcohol synthesis from syngas. The catalyst was fabricated via structural topological transformation of CuCo2O4 spinel precursor.