One-Pot Synthesis of Cu-Nanocluster-Decorated Brookite TiO2Quasi-Nanocubes for Enhanced Activity and Selectivity of CO2Photoreduction to CH4

Recent Progress on Ligand-Protected Metal Nanoclusters in Photocatalysis

The reckless use of non-replenishable fuels by the growing population for energy and the resultant incessant emissions of hazardous gases and waste products into the atmosphere have insisted that scientists fabricate materials capable of managing these global threats at once. In recent studies, photocatalysis has been employed to focus on utilizing renewable solar energy to initiate chemical processes with the aid of semiconductors and highly selective catalysts. A wide range of nanoparticles has showcased promising photocatalytic properties. Metal nanoclusters (MNCs) with sizes below 2 nm, stabilized by ligands, show discrete energy levels and exhibit unique optoelectronic properties, which are vital to photocatalysis. In this review, we intend to compile information on the synthesis, true nature, and stability of the MNCs decorated with ligands and the varying photocatalytic efficiency of metal NCs concerning changes in the aforementioned domains. The review discusses the photocatalytic activity of atomically precise ligand-protected MNCs and their hybrids in the domain of energy conversion processes such as the photodegradation of dyes, the oxygen evolution reaction (ORR), the hydrogen evolution reaction (HER), and the CO₂ reduction reaction (CO₂RR).

A p-n Junction by Coupling Amine-Enriched Brookite-TiO2 Nanorods with CuxS Nanoparticles for Improved Photocatalytic CO2 Reduction

Photocatalytic CO₂ reduction is a promising technology for reaching the aim of "carbon peaking and carbon neutrality", and it is crucial to design efficient photocatalysts with a rational surface and interface tailoring. Considering that amine modification on the surface of the photocatalyst could offer a favorable impact on the adsorption and activation of CO₂, in this work, amine-modified brookite TiO₂ nanorods (NH₂-B-TiO₂) coupled with Cu_xS (NH₂-B-TiO₂-Cu_xS) were effectively fabricated via a facile refluxing method. The formation of a p-n junction at the interface between the NH₂-B-TiO₂ and the Cu_xS could facilitate the separation and transfer of photogenerated carriers. Consequently, under light irradiation for 4 h, when the Cu_xS content is 16%, the maximum performance for conversion of CO₂ to CH₄ reaches at a rate of 3.34 μmol g^-1 h^-1 in the NH₂-B-TiO₂-Cu_xS composite, which is approximately 4 times greater than that of pure NH₂-B-TiO₂. It is hoped that this work could deliver an approach to construct an amine-enriched p-n junction for efficient CO₂ photoreduction.

Non-Noble Plasmonic Metal-Based Photocatalysts

Solar-to-chemical energy conversion via heterogeneous photocatalysis is one of the sustainable approaches to tackle the growing environmental and energy challenges. Among various promising photocatalytic materials, plasmonic-driven photocatalysts feature prominent solar-driven surface plasmon resonance (SPR). Non-noble plasmonic metals (NNPMs)-based photocatalysts have been identified as a unique alternative to noble metal-based ones due to their advantages like earth-abundance, cost-effectiveness, and large-scale application capability. This review comprehensively summarizes the most recent advances in the synthesis, characterization, and properties of NNPMs-based photocatalysts. After introducing the fundamental principles of SPR, the attributes and functionalities of NNPMs in governing surface/interfacial photocatalytic processes are presented. Next, the utilization of NNPMs-based photocatalytic materials for the removal of pollutants, water splitting, CO₂ reduction, and organic transformations is discussed. The review concludes with current challenges and perspectives in advancing the NNPMs-based photocatalysts, which are timely and important to plasmon-based photocatalysis, a truly interdisciplinary field across materials science, chemistry, and physics.

Promoting photocatalytic CO2 reduction to CH4 via a combined strategy of defects and tunable hydroxyl radicals

A well-designed photocatalyst with excellent activity and selectivity is crucial for photocatalytic CO₂ conversion and utilization. TiO₂ is one of the most promising photocatalysts. However, its excessive surface oxidation potential and insufficient surface active sites inhibit its activity and photocatalytic CO₂ reduction selectivity. In this work, highly dispersed Bi₂Ti₂O₇ was introduced into defective TiO₂ to adjust its oxidation potential and the generation of radicals, further inhibiting reverse reactions during the photocatalytic conversion of CO₂. Moreover, an in situ topochemical reaction etching route was designed, which achieved defective surfaces, a contacted heterophase interface, and an efficient electron transfer path. The optimized heterophase photocatalyst exhibited 93.9% CH₄ selectivity at a photocatalytic rate of 6.8 μmol·g^-1·h^-1, which was 7.9 times higher than that of P25. This work proposes a feasible approach to fabricating photocatalysts with well-designed band structures, highly dispersed heterophase interfaces, and sufficient surface active sites to effectively modulate the selectivity and activity of CO₂ photoreduction by manipulating the reaction pathways.

Brookite TiO2 Nanoparticles Decorated with Ag/MnOx Dual Cocatalysts for Remarkably Boosted Photocatalytic Performance of the CO2 Reduction Reaction

The solar-driven CO₂ reduction reaction (CO₂RR) for producing chemical fuels is considered to be a promising approach to dealing with the growing energy crisis and greenhouse effect. Herein, novel Ag/MnO_x dual-cocatalyst-decorated brookite titania (BT) nanoparticles with remarkably boosted photocatalytic CO₂RR performance are prepared through a facile photodeposition method. The resultant xAg-BT-yMn composite with optimal cocatalyst content delivers amazing CO/CH₄ yields of 31.70/129.98 μmol g^-1 with an overall photoactivity of 1103.28 μmol g^-1 h^-1, 11.98 times higher than that of the BT nanoparticles alone. Further investigations demonstrate that the dual cocatalysts decorating the BT nanoparticles not only effectively retard the photoinduced charge recombination but also significantly vary the surface chemical feature to promote the adsorption/activation of the reactants (CO₂/H₂O). In addition, the Ag nanoparticles can broaden the spectral response region, while the MnO_x cocatalyst can promote the CH₄ product selectivity and the water oxidation reaction. The synergistic effect of Ag/MnO_x dual cocatalysts on the BT nanoparticles renders a remarkably boosted CO₂RR performance, which provides a simple yet general synthesis strategy for brookite titania-based photocatalysts with high-performance solar-driven CO₂ conversion.

One-pot synthesis of N,S-doped pearl chain tube-loaded Ni3S2 composite materials for high-performance lithium-air batteries

To improve the high reversibility of lithium-air batteries, an air electrode needs to have excellent electrochemical performance and spatial structure. Ni3S2 nanoparticles are loaded onto an N,S-doped pearl chain tube (N,S-PCT) by a method called quasi-chemical vapor deposition (Q-CVD). Additionally, N and S are doped during the synthesis process, thereby forming an ideal pipe rack-like structure. The large amount of space in the tube rack can provide sufficient storage to act as a buffer for the discharge products, and the interconnected tubes can effectively promote the dispersion of O2 and electrolyte. The addition of Ni3S2 nanoparticles effectively reduces the charge transfer resistance, thereby increasing the electron mobility of the cathode. Ni3S2@N,S-PCT cathodes effectively improve the cycling and high-rate performance of lithium-air batteries, demonstrating an ultrahigh discharge capacity of 16 733.7 mA h g-1 at a current density of 400 mA g-1 and an ultrahigh discharge capacity of 5088.1 mA h g-1 at a current density of 1000 mA g-1. When the cut-off capacity is 1000 mA h g-1, the battery with the Ni3S2@N,S-PCT-800 electrode can achieve cycling stability for 148 cycles. This research provides a new solution for the design of lithium-air batteries with high electrocatalytic performance.

Mechanistic Understanding on the Role of Cu Species over the CuO x /TiO2 Catalyst for CO2 Photoreduction

Incorporation of earth-abundant Cu is one of the most important approaches to improve the practicability of TiO2 for photoreduction of CO2 into value-added solar fuels. However, the molecular insight on the role of Cu is complicated and far from understood. We performed a first principle calculation on the anatase (101) surface modified by a single Cu atom deposited on the surface (CuS) or doped in the lattice (CuL). It is demonstrated the CuL is clearly more stable than the CuS and could promote the formation of oxygen vacancy (Vo) greatly. The CuS plays a role of donor, while the CuL is electronically deficient and becomes a global electron trapper. If a Vo is introduced, the excess electrons would immigrate to the empty gap state of the CuL and make it half-filled in some case, which implies its metallic characters and improved conductivity; meanwhile, the formation of Ti3+ is suppressed. Judging from the adsorption energies, it is the Vo that primarily improves the adsorption of CO2 in both linear and bent states, and the CuS could hardly stabilize CO2 more, while the promotion effect of Vo could even be counteracted by the CuL due to its electronic deficiency. The reduction pathways (CO2* → CO* + O*) show that, with the assistance of the CuS, linear CO2 could directly transform into the carbonate-like geometry vertically binding to the surface, and the intermediate configuration of the bent CO2 horizontally bridging the Vo could be successfully skipped. Therefore, the barrier of the rate-determining transformation could be lowered from 0.75 to 0.39 eV. Furthermore, it is found the strong adsorption of the produced CO by the CuS might retard the smooth going of the catalytic process.

Surface strategies for catalytic CO2 reduction: from two-dimensional materials to nanoclusters to single atoms

This work constructively reviewed and predicted the surface strategies for catalytic CO₂ reduction with 2D material, nanocluster and single-atom catalysts