Recent advances and perspectives in cobalt‐based heterogeneous catalysts for photocatalytic water splitting,CO_(2) reduction,and N_(2) fixation

Solar‐driven conversion of carbon dioxide,water and nitrogen into high value‐added fuels(e.g.H_(2),CO,CH_(4),CH_(3)OH,NH_(3) and so on)is regarded as an environmental‐friendly and ideal route for relieving the greenhouse gas effect and countering energy crisis,which is an attractive and challenging topic.Hence,various types of photocatalysts have been developed successively to meet the requirements of these photocatalysis.Among them,cobalt‐based heterogeneous catalysts emerge as one of the most promising photocatalysts that open up alluring vistas in the field of solar‐to‐fuels conversion,which can effectively enhance photocatalytic efficiency by extending light absorption range,promoting charge separation,providing active sites,and lowering reaction barrier.In this review,we first present the working principles of cobalt‐based heterogeneous catalysts for photocatalytic water splitting,CO_(2) reduction,and N_(2) fixation.Second,five efficient strategies including surface modification,morphology modulation,crystallinity controlling,crystal engineering and doping,are discussed for improving the photocatalytic performance with different types cobalt‐based catalysts(cobalt nanoparticles and single atom,oxides,sulfides,phosphides,MOFs,COFs,LDHs,carbide,and nitrides).Third,we outline the applications for the state‐of‐the‐art photocatalytic CO_(2) reduction and water splitting,and nitrogen fixation over cobalt‐based heterogeneous catalysts.Finally,the central challenges and possible improvements of cobalt‐based photocatalysis in the future are presented.The purpose of this review is to summarize the past experience and lessons,and provide reference for the further development of cobalt‐based photocatalysis technology.

Filtering and regret network for spacecraft component segmentation based on gray images and depth maps

Identifying and segmenting spacecraft components is vital in many on-orbit space missions,such as on-orbit maintenance and component recovery.Integrating depth maps with visual images has been proven effective in improving segmentation accuracy.However,existing methods ignore the noise and fallacy in collected depth maps,which interfere with the network to extract representative features,decreasing the final segmentation accuracy.To this end,this paper proposes a Filtering and Regret Network(FRNet)for spacecraft component segmentation.The FRNet incorporates filtering and regret mechanisms to suppress the abnormal depth response in shallow layers and selectively reuses the filtered cues in deep layers,avoiding the detrimental effects of low-quality depth information while preserving the semantic context inherent in depth maps.Furthermore,a two-stage feature fusion module is proposed,which involves information interaction and aggregation.This module effectively explores the feature correlation and unifies the multimodal features into a comprehensive representation.Finally,a large-scale spacecraft component recognition dataset is constructed for training and evaluating spacecraft component segmentation algorithms.Experimental results demonstrate that the FRNet achieves a state-of-the-art performance with a mean Intersection Over Union(mIOU)of 84.13%and an average inference time of 133.2 ms when tested on an NVIDIA RTX 2080 SUPER GPU.

Adhesion Characteristics of a Novel Synthetic Polydimethylsiloxane for Bionic Adhesive Pads

Materials with appropriate adhesive properties are suitable for the fabrication of bionic adhesive pads. In this study, a novel polydimethylsiloxane （PDMS） material enhanced with two types of crosslinkers, carbon nanotubes and graphene sheets, was fabricated. The Contact Angle （CA） and cross-sectional morphology of the new material were investigated and observed using a CA meter and Scanning Electron Microscopy （SEM）, respectively. CA measurements indicate that the surface energy of the novel material is twice that of the common PDMS material. SEM observations show that carbon nanotubes and graphene sheets are well dispersed in the polymer, a feature that improves the mechanical properties of the new material. The adhesive performance of this novel composite was tested on an in-house fabricated friction machine. Results show that at a preload of only 50 mN, the adhesion of the novel PDMS material is up to -3.7 times that of common PDMS. The maximum macroscale shear strength and normal adhesion reach 4 N·cm^-2 and 1 N·cm^-2, respectively. The adhesive capability of the material is maintained even after hundreds of times of repeated use. This novel material exhibits excellent adhesion, sufficiently high elastic modulus and high repeatability at low preloads.

Comparative study on the influence of AI component at GaAIAs layer for GaAs/A1GaAs photocathode

We designed two transmission-mode GaAs/AIGaAs photocathodes with different AlxGa1-xAs layers, one has an AlxGal-xAs layer with the Al component ranging from 0.9 to 0, and the other has a fixed AI component 0.7. Using the first-principle method, we calculated the electronic structure and absorption spectrum ofAlx Ga1-x As at x = 0, 0.25, 0.5, 0.75 and 1, calculation results suggest that with the increase of the A1 component, the band gap of AlxGa1-xAs increases. Then we activated the two samples, and obtained the spectral response curves and quantum efficiency curves; it is found that sample 1 has a better shortwave response and higher quantum efficiency at short wavelengths. Combined with the band structure diagram of the transmission-mode GaAs/AIGaAs photo- cathode and the fitted performance parameters, we analyze the phenomenon. It is found that the transmission-mode GaAs/AlGaAs photocathode with variable AI component and various doping structure can form a two-stage built-in electric field, which improves the probability of shortwave response photoelectrons escaping to the vacuum. In con- clusion, such a structure reduces the influence of back-interface recombination, improves the shortwave response of the transmission-mode photocathode.