Converting solar energy into fuels/chemicals through photochemical approaches holds significant promise for addressing global energy demands. Currently, semiconductor photocatalysis combined with redox techniques has been intensively researched in pollutant degradation and secondary energy generation owing to its dual advantages of oxidizability and reducibility; however, challenges remain, particularly with improving conversion efficiency. Since graphene’s initial introduction in 2004, three-dimensional (3D) graphene-based photocatalysts have garnered considerable attention due to their exceptional properties, such as their large specific surface area, abundant pore structure, diverse surface chemistry, adjustable band gap, and high electrical conductivity. Herein, this review provides an in-depth analysis of the commonly used photocatalysts based on 3D graphene, outlining their construction strategies and recent applications in photocatalytic degradation of organic pollutants, H₂ evolution, and CO₂ reduction. Additionally, the paper explores the multifaceted roles that 3D graphene plays in enhancing photocatalytic performance. By offering a comprehensive overview, we hope to highlight the potential of 3D graphene as an environmentally beneficial material and to inspire the development of more efficient, versatile graphene-based aerogel photocatalysts for future applications.

A detailed analysis of the effects of magnesium on the microstructure of hypereutectic Al–20Si alloys is provided in this study. Experimental results show that the addition of Mg significantly refines the primary silicon phase relative to the unmodified Al–20Si alloy, transforming its morphology from a complex form to a singular plate-like structure. Notably, for the first time, equiaxed aluminum grains appear in the aluminum matrix under conventional solidification conditions. The generation of these grains is closely related to the quenching effect caused by rapid cooling during metal mold casting, which promotes the generation of equiaxed aluminum grains within tightly constrained temporal and spatial parameters. The Al–Si eutectic structure exhibits a regular lamellar morphology, with an average eutectic silicon spacing of 930.97 nm. The phase analysis shows that the alloy mainly consists of Al, Si, and Mg₂Si phases after the addition of Mg. With the increase in Mg concentration, the diffraction peaks for Al(200) and Si(220) first shift to lower angles and then move to higher angles, along with significant peak broadening. Ambient temperature mechanical testing indicates that tensile strength first increases with increasing Mg concentration, then declines, with the highest tensile strength of 235.1 MPa at 3 wt.% Mg in the Al–20Si alloy. The fracture mechanism of the testing specimens changes from cleavage fracture to ductile fracture. Microhardness testing indicates a continuous increase in the hardness of the aluminum matrix with rising Mg concentration; the hardness of primary silicon declines first and then increases, whereas the hardness of the eutectic structure exhibits a first increase followed by a decline.

High-load sliding components, including gun barrels, are susceptible to accelerated wear and damage due to coupled thermal-mechanical stresses and reciprocating frictional conditions. Therefore, enhancing their operational lifespan requires the application of wear-resistant coatings with high melting points for effective surface protection. In this study, Ta-10W alloy coatings were deposited on CrNi3MoVA steel substrates through electricspark deposition, focusing on deposition voltage as a critical parameter. Experimental results indicate that the Ta-10W coatings are primarily composed of α-Fe, α-Ta₂O₅, δ-Ta₂O₅, α-Ta(W), and Fe-W intermetallic phases. An increase in deposition voltage facilitates enhanced melting and mass transfer, thereby promoting solid solution and oxidation strengthening, which results in improved hardness. However, higher voltages also induce defects such as porosity and microcracks. Hardness measurements and friction-wear tests demonstrate that coatings deposited at 80 V exhibit optimal performance, attaining the highest hardness (~753 HV) and a friction coefficient similar to that at 60 V. Conversely, the friction coefficient increases at 100 V due to defects and coating spalling. The wear mechanism transitions from adhesive wear at 60 V to adhesive wear with minor plastic deformation at 80 V and ultimately to spalling wear at 100 V. Finite element thermomechanical simulations reveal that increasing voltage significantly elevates the equivalent interfacial stress (600–1150 MPa), thus correlating with the propensity for microcracks to propagate into longitudinal semi-penetrating cracks at elevated voltages. This study establishes a theoretical foundation for optimizing electricspark deposition process parameters and contributes to the reliability design of Ta-W alloy coatings.

The chemical modification of Al–20Si alloy in the case of incorporation of rare earth cerium (Ce) is investigated in this study, focusing on the resulting microstructure evolution and changes in mechanical properties and hardness before and after cerium modification. The microstructure of the cerium-modified alloy is composed of the aluminum matrix, eutectic silicon, and primary silicon phases, as well as the Al₂Si₂Ce phase, a cerium-containing solid solution, and the α-Al₁₁Ce₃ phase. It is worth noting that this study reports for the first time an unusual phenomenon in which the addition of cerium raises tensile strength of the alloy while concurrently decreasing its surface hardness. The increase in tensile strength is mainly ascribed to the refinement of primary silicon. On the contrary, the reduction of hardness is explained by the competition between Ce-induced toughening and solid solution strengthening, as well as the generation of the relatively soft α-Al₁₁Ce₃ phase. Mechanical properties at room temperature show that the greatest tensile strength of 153 ± 7 MPa is reached at a cerium concentration of 0.7 wt.%, while the corresponding elongation of the mechanical specimen is 1.36 ± 0.287. The fracture mechanism changes from cleavage fracture in the unmodified alloy to ductile fracture after Ce addition.

Developing efficient non-precious electrocatalysts for the hydrogen evolution reaction (HER) is crucial to advancing scalable green hydrogen generation. Herein, vertically aligned TiO₂ nanotube arrays were directly grown on Ti substrates via electrochemical anodization and subsequently employed as a scaffold for the in situ hydrothermal growth of MoS₂ nanosheets. Among the investigated electrodes, MoS₂/TNT-2 exhibits the best electrochemical HER performance, achieving a current density of 10 mA cm⁻² at an overpotential of 353 mV in 1 M KOH. Moreover, the electrode maintains good electrochemical stability during a 24 h chronoamperometric test and after 2000 cyclic voltammetry sweeps. This work provides a facile route for constructing self-supported MoS₂/TiO₂ heterostructured electrodes for alkaline HER.