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Direct and Efficient Conversion from Low-Quality Graphite to High-Quality Graphene Nanoplatelets
摘要： Low-quality graphite (L-graphite), containing various impurities (e.g., metals and inorganics), can be directly and efficiently converted into high-quality iodine-doped graphene nanoplatelets (HIGnPs) via mechanochemical ball-milling in the presence of iodine (I2) with subsequent work-up procedures. Despite using L-graphite, the resultant HIGnPs show high-quality characteristics, including large specific surface area (969 m2 g?1), lower metallic residues, and well-maintained graphitic structure. In addition, HIGnPs display remarkable electrocatalytic performance for oxygen reduction reaction (ORR), involving benefits such as higher selectivity, longer-term stability, and better tolerance to methanol crossover/CO poisoning effects. Therefore, simple mechanochemical ball-milling in solid state can produce high-quality graphene nanoplatelets in large quantity at low-cost for commercialization, regardless of the initial quality of the graphite.
关键词： Oxygen reduction reaction,Mechanochemical reaction,High-quality graphene,ball-milling,Low-quality graphite
更新于2025-09-10 09:29:36
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In situ Raman spectroscopic evidence for oxygen reduction reaction intermediates at platinum single-crystal surfaces
摘要： Developing an understanding of structure–activity relationships and reaction mechanisms of catalytic processes is critical to the successful design of highly efficient catalysts. As a fundamental reaction in fuel cells, elucidation of the oxygen reduction reaction (ORR) mechanism at Pt(hkl) surfaces has remained a significant challenge for researchers. Here, we employ in situ electrochemical surface-enhanced Raman spectroscopy (SERS) and density functional theory (DFT) calculation techniques to examine the ORR process at Pt(hkl) surfaces. Direct spectroscopic evidence for ORR intermediates indicates that, under acidic conditions, the pathway of ORR at Pt(111) occurs through the formation of HO2*, whereas at Pt(110) and Pt(100) it occurs via the generation of OH*. However, we propose that the pathway of the ORR under alkaline conditions at Pt(hkl) surfaces mainly occurs through the formation of O2?. Notably, these results demonstrate that the SERS technique offers an effective and reliable way for real-time investigation of catalytic processes at atomically flat surfaces not normally amenable to study with Raman spectroscopy.
关键词： density functional theory,in situ Raman spectroscopy,electrochemical surface-enhanced Raman spectroscopy,oxygen reduction reaction,platinum single-crystal surfaces
更新于2025-09-10 09:29:36
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Aluminum and Nitrogen Codoped Graphene: Highly Active and Durable Electrocatalyst for Oxygen Reduction Reaction
摘要： The development of highly active and exceedingly durable electrocatalyst at low cost for oxygen reduction reaction (ORR) is extremely desirable, but remains to be a grand challenge. Over the past decade, the transitional-metal (e.g., Fe, Co, Ni) and N codoped graphene materials have attracted most attention as the state-of-the-art non-precious-metal-based effective electrocatalyst for ORR, but still entail unsatisfactory issues such as moderate activity and life. Herein, the main-group-metal Al and N codoped graphene (ANG) is successfully fabricated via thermal annealing treatment of N-doped graphene with aluminum tri-(8-hydroxyquinoline). As a highly effective electrocatalyst for ORR, the as-prepared ANG exhibits not only high electrocatalytic activity that even outperforms the commercial Pt/C, but also good durability in both three-electrode cell and Zn-air battery. Theory calculations show that the inhomogeneous charge density distribution and the interaction between Al and N are mainly responsible for the marked enhancement of ORR activity. The designed ANG electrocatalysts will provide a perspective application in energy storage and promote further exploration of main-group-element-based inexpensive, active and durable electrocatalysts.
关键词： N-doped graphene,noble-metal free,Al-doped graphene,oxygen reduction reaction,electrocatalyst
更新于2025-09-09 09:28:46
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Electronic Tuning of Metal Nanoparticles for Highly Efficient Photocatalytic Hydrogen Peroxide Production
摘要： We here present an innovative approach to increase the electron density of metallic Pd nanoparticles loaded on TiO2 photocatalysts by coordinating Pd with surface-anchored organic ligands. X-ray photoelectron spectroscopy and X-ray absorption near edge structure measurements confirm the negative charge on the Pd nanoparticle induced by electron donation from amine groups of the ligands. The electronically modified Pd on TiO2 exhibits unprecedentedly high photocatalytic H2O2 production from O2 reduction. Mechanistic investigations suggest that the enhanced performance results from electronic tuning of Pd nanoparticles, leading to enhanced charge separation on TiO2 support, improved activity of Pd nanoparticles as an oxygen reduction center, and improved selectivity for O2 reduction to produce H2O2.
关键词： immobilized organic ligands,oxygen reduction reaction,electronic tuning,hydrogen peroxide,photocatalysis
更新于2025-09-04 15:30:14
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Synthesis and Characterizations of Zinc Oxide on Reduced Graphene Oxide for High Performance Electrocatalytic Reduction of Oxygen
摘要： Electrocatalysts for the oxygen reduction (ORR) reaction play an important role in renewable energy technologies, including fuel cells and metal-air batteries. However, development of cost effective catalyst with high activity remains a great challenge. In this feature article, a hybrid material combining ZnO nanoparticles (NPs) with reduced graphene oxide (rGO) is applied as an efficient oxygen reduction electrocatalyst. It is fabricated through a facile one-step hydrothermal method, in which the formation of ZnO NPs and the reduction of graphene oxide are accomplished simultaneously. Transmission electron microscopy and scanning electron microscopy profiles reveal the uniform distribution of ZnO NPs on rGO sheets. Cyclic voltammograms, rotating disk electrode and rotating ring disk electrode measurements demonstrate that the hierarchical ZnO/rGO hybrid nanomaterial exhibits excellent electrocatalytic activity for ORR in alkaline medium, due to the high cathodic current density (9.21 × 10?5 mA/cm2), positive onset potential (?0.22 V), low H2O2 yield (less than 3%), and high electron transfer numbers (4e from O2 to H2O). The proposed catalyst is also compared with commercial Pt/C catalyst, comparable catalytic performance and better stability are obtained. It is expected that the ZnO/rGO hybrid could be used as promising non-precious metal cathode in alkaline fuel cells.
关键词： reduced graphene oxide,zinc oxide,non-precious-metal catalyst,oxygen reduction reaction
更新于2025-09-04 15:30:14
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[SpringerBriefs in Materials] Anisotropic Metal Chalcogenide Nanomaterials (Synthesis, Assembly, and Applications) || Applications
摘要： Interest in anisotropic 1D and 2D nanostructures has been steadily increasing due to their large surface area, quantum con?nement effect, and superior optoelectrical or thermoelectrical properties. Anisotropic geometry and size reduction comparable to the Debye length can alter the optical, electric, and magnetic properties of the bulk counterparts. Focusing on MCs prepared in solution the major interests for practical applications are thermoelectric power phases, generation or electronic device cooling, high performance electrodes for batteries, nanocrystal-based photovoltaic devices, and photodetectors. Recently, new potential uses of the solution-based MC nanocrystals are being investigated, which include localized surface plasmon resonance (LSPR) and oxygen reduction reaction (ORR). MC thin ?lms prepared by the vacuum process have shown the possibilities as new class of materials such as topological insulator, semiconductor with a high electron mobility, and superconductor. Although the organic surfactants indispensable in solution chemistry diminish such superior physical properties, solution-based approach has large room to achieve such physical properties. This chapter will introduce recent advances in the practical applications of the anisotropic MC nanocrystals, and introduce brie?y the potential applications.
关键词： thermoelectric,oxygen reduction reaction,photodetector,metal chalcogenides,localized surface plasmon resonance,photovoltaic,superconductor,topological insulator,anisotropic nanostructures
更新于2025-09-04 15:30:14
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Three-Dimensional Superlattices Based on Unusual Chalcogenide Supertetrahedral In–Sn–S Nanoclusters
摘要： Reported here are two novel metal chalcogenide superlattices built from unusual supertetrahedral TO2-InSnS clusters. With regard to only one previously reported case of a TO2-InS-based 2D-layered structure, such a combination of In?Sn?S components is leading to the first observation of 3D superlattices based on TO2-InSnS clusters. Besides, these title semiconducting materials also display good performance on the electrocatalytic oxygen reduction reaction.
关键词： 3D superlattices,metal chalcogenide,electrocatalytic oxygen reduction reaction,supertetrahedral clusters
更新于2025-09-04 15:30:14