Junkai Ren

Junkai Ren
Umeå University | UMU · Department of Physics

PhD

About

36
Publications
3,157
Reads
How we measure 'reads'
A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more
517
Citations

Publications

Publications (36)
Article
Full-text available
Rational regulation of the composition and structure of electrocatalysts is crucial to the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Herein, a new electrocatalyst of nickel phosphate microprism (VSB/NiPO) is developed via a simple solvothermal reaction. The microprism is mainly composed of Versailles‐Santa Barbara‐5 (VS...
Article
Full-text available
Heterostructures formed by anatase nanotitania and bidimensional semiconducting materials are expected to become the next-generation photocatalytic materials with an extended operating range and higher performances. The capability of fabricating optically transparent photocatalytic thin films is also a highly demanded technological issue, and incre...
Article
In this study, carbon dots (CDs) synthesized by hydrothermal method with amino-rich surface exhibit tunable fluorescence across entire visible range by simply controlling the concentration. A comprehensive comparison has been performed for the first time between concentration-induced aggregation of the single-type CDs and electrostatic-induced aggl...
Article
Full-text available
Constructing low-cost, high-efficient, and stable electrocatalysts is crucial for large-scale and sustainable water-to-hydrogen conversion. Herein, the combination approaches of hydrothermal, annealing and electrodeposition have been used to fabricate a novel defect-rich electrocatalyst, Ni(OH)2/NiO-C/WO3 HAs, that is composed of WO3 core with Ni(O...
Article
Silane-Functionalized Carbon Dots The shell represents the 3D-structure of silane-functionalized carbon dots (SiCDs) polymerized nanohybrid with a ball-and-stick figure (Si-O-Si covalent bond links). The inside pearl represents the multicolor luminescence of SiCDs. The bubbles around the shells indicate five representative applications (form left t...
Article
Nanomaterials usually manifest unique properties in solutions but will be undermined in the solid state. It is necessary to incorporate them into substrates or hybrid them with other functional materials for multiple devices and applications. Though there are a variety of methods to inherit their intrinsic properties like fluorescent and mechanical...
Article
Full-text available
Hexagonal boron nitride (h-BN) is one of the most attractive 2D materials due to its remarkable properties. Combining h-BN with other components (e.g. graphene, carbonitride, semiconductors) to form heterostructures opens new perspectives to developing advanced functional devices. In this review, we have highlighted the state-of-the-art in h-BN het...
Article
The widespread implementation of water splitting urgently requires low-cost, effective and stable electrocatalysts for the industrial oxygen evolution reaction (OER) that can reach a large current density (>500 mA cm⁻²). Herein, we report a facile solvothermal strategy to fabricate a binder-free electrode of Fe-S-NiMoO4/MoO3 with nanorods array uni...
Article
Full-text available
The absence of an ideal solid matrix with resistance to harsh conditions for carbon dots (CDs) and high transmittance in the visible/near infrared region is the bottleneck in CD applications. In this study, we show that a stable rigid structure can be formed between CDs and organically modified silicates (ormosil) gel when CDs are incorporated into...
Article
Hydrogen generation by alkaline electrochemical water splitting urgently requires new techniques capable of fabricating efficient and robust electrocatalysts for hydrogen evolution reaction (HER). However, it remains a major challenge to achieve this aim through a conjoint modulation in morphology and electronic structure. Herein, a metal-organic f...
Article
Hexagonal boron nitride (h-BN) nanodots of 10 nm have been synthesized via top-down route from bulk powders. A combination of ultrasonic and thermal treatments in phosphoric acid has been used to achieve edge etching and size reduction to the nanoscale. A new emission in the ultraviolet region, correlated to a characteristic infrared-active vibrati...
Article
Full-text available
The fabrication of optically active heterostructures in the shape of mesostructured thin films is a highly challenging task. It requires an integrated process to allow in one-step incorporating the two-dimensional materials within the mesoporous ordered host without disrupting the pore organization. Hexagonal boron nitride (BN) nanosheets have been...
Article
In this work, dual-luminophore self-referenced pressure sensitive paint (PSP) was prepared with siloxane precursors by using copolymerizable silane-functionalized carbon dots (SiCDs) as a reference probe and a newly synthesized silane-modified ruthenium complex (Ru-silane) as the sensitive probe respectively. The PSP is fully sprayable in the prepa...
Article
Full-text available
Functionalization of boron nitride (BN) materials with hydroxyls has attracted great attention to accomplish better performances at micro- and nanoscale. BN surface hydroxylation, in fact, induces a change in properties and allows expanding the fields of application. In this review, we have summarized the state-of-the-art in developing hydroxylated...
Article
Full-text available
Carbon dots (CDs) are highly-emissive nanoparticles obtained through fast and cheap syntheses. The understanding of CDs’ luminescence, however, is still far from being comprehensive. The intense photoluminescence can have different origins: molecular mechanisms, oxidation of polyaromatic graphene-like layers, and core-shell interactions of carbonac...
Article
Full-text available
During the storage of agricultural products, the oxygen concentration in the packages represents the level of food respiration and hence indicates its freshness. Herein, self-referenced photoluminescent oxygen sensitive fibrous membranes were prepared, with the inclusion of an oxygen-sensitive probe, i.e. tris (4,7-diphenyl-1,10-phenanthroline) rut...
Article
In recent years, carbon dots (CDs) have attracted considerable attention for their potential application in photonics and optoelectronics. One of the main limitations in realizing efficient and reliable solid-state devices is the aggregation-caused quenching effect. At a short distance, the mutual interaction among nanoparticles enhances the non-ra...
Cover Page
Full-text available
Despite the potential applications in several technological fields, 2D materials are at their early stages. Among them, boron nitride-based systems are still far from having been comprehensively studied. The possibilities of practical applications extend to very varied fields, from mechanics to optics. However, from careful observation of the exper...
Article
Full-text available
The discovery of graphene has paved the way for intense research into 2D materials which is expected to have a tremendous impact on our knowledge of material properties in small dimensions. Among other materials, boron nitride (BN) nanomaterials have shown remarkable features with the possibility of being used in a large variety of devices. Photoni...
Article
Bottom-up synthesis of fluorescent boron-nitride based dots is a challenging task because an accurate design of the structure-properties relationship is, in general, difficult to achieve. Incorporation of the dots into a solid-state matrix is also another important target to develop light-emitting devices. Two-colour fluorescent boron oxynitride na...
Article
Luminescent materials with high efficiency, narrow emission bandwidth and long emission wavelength have attracted extensive attention in recent years. However, for novel luminescent carbon dots, it is still a major challenge to obtain these properties simultaneously. Here, this type of carbon dot was proposed using 1,4-diaminonaphthalene as the ini...
Article
Herein we report on a biluminophore fast-responding pressure sensitive coating with a bi-layer structure prepared by a non-sensitive reference base paint and subsequently a classic polymer-ceramic pressure sensitive paint (PSP). The coating procedure is fully sprayable and allows the separation of the two luminophores in each layer to prevent their...
Article
Polymer blends with self-healing capability when damaged have received increasing interests and have been developing rapidly because of their many potential applications. Here, the polymer blend comprising of thermoplastic polyurethane (TPU) and polycaprolactone (PCL) as shape memory matrix was initially prepared by melting blending, and then the m...
Article
Herein, we report a simple in-situ hydrothermal synthesis method to prepare a novel three-dimensional (3D) nanoflowers consisting of few-layered and enlarged interlayer spacing MoS2 nanoflakes via restricting the polymerization of guar gum and the growth of MoS2. In this process, hexaammonium molybdate ((NH4)6Mo7O24·4H2O) and thiourea (CH4N2S) served...
Article
In this work, an efficient strategy is proposed to obtain single‐type carbon dots with precisely controlled up/down‐conversion photoluminescence under both liquid and solid states. Tunable fluorescence from green to red color can be achieved via either changing the solvents or matrices composition, or adjusting the concentration of carbon dots. In...
Article
In this work, an efficient method is developed to prepare silane‐functionalized red‐emissive carbon dots and carbon dots gel glasses with arbitrary loading fraction (0–100%). The as‐prepared materials possess strong photoluminescence and significant third‐order nonlinear optical performances. The optical properties can be tuned by either changing s...
Article
This paper presented a unique lyophilic but nonwettable property of organosilane-polymerized carbon dots inverse opals photonic crystals (SiCDPCs) with close-cell structure. Little stopband shift was observed for the SiCDPCs when being immersed into the solvents such as isopropanol, olive oil, DMSO, hexane, silicone oil, ethanediol and etc, but kee...
Article
This paper demonstrates multi-functional optical properties of organosilane-polymerized carbon dots inverse opals, such as tricolor-fluorescence, fluorescence enhancement, multi-color mcio-patterned for anti-fake and a thermal-induced blueshift of bandgap. It is of...
Article
A facile, environment-friendly and one-pot synthesis method for the preparation of high performance PtRu electrocatalysts on the multiwalled carbon nanotubes (MWCNTs) is reported. Herein, bimetallic PtRu electrocatalysts are deposited onto polydopamine (Pdop) –functionalized MWCNTs by mildly stirring at room temperature. Without the use of expensiv...
Article
In this study, the lightweight, hydrophobic and porous cellulose-based aerogels (CAGs) were synthesized through a freeze–drying process using waste newspaper as the only raw material. After crosslinking with glutaraldehyde and treatment with trimethylchlorosilane (TMCS) using a simple thermal chemical vapor deposition process, the resulting CAGs be...
Article
In this study we introduced a facile hydrothermal approach to fabricate a core–shell Au@ZIF-8 hybrid nanomaterial. A successful preparation of monodisperse core–shell Au@ZIF-8 hybrid material was achieved through easy changes of the reaction conditions. The water-soluble anticancer drug, doxorubicin hydrochloride (DOX·HCl), was loaded into the hybr...

Questions

Questions (2)
Question
Is there a good way to measure FTIR of samples in concentrated sulfuric acid? Thanks
Question
Is there a free software to calculate CRI, CQS, Rf, Rg, etc. according to the spectrum?

Network

Cited By