Clinical applications of current photodynamic therapy (PDT) agents are often limited by their low singlet oxygen (1O2) quantum yields, as well as by photobleaching and poor biocompatibility. Here we present a new PDT agent based on graphene quantum dots (GQDs) that can produce 1O2 via a multistate sensitization process, resulting in a quantum yield of ~1.3, the highest reported for PDT agents. The GQDs also exhibit a broad absorption band spanning the UV region and the entire visible region and a strong deep-red emission. Through in vitro and in vivo studies, we demonstrate that GQDs can be used as PDT agents, simultaneously allowing imaging and providing a highly efficient cancer therapy. The present work may lead to a new generation of carbon-based nanomaterial PDT agents with overall performance superior to conventional agents in terms of 1O2 quantum yield, water dispersibility, photo- and pH-stability, and biocompatibility.

At room temperature, glasses are known to be brittle and fracture upon deformation. Zheng et al. show that, by exposing amorphous silica nanostructures to a low-intensity electron beam, it is possible to achieve dramatic shape changes, including a superplastic elongation of 200% for nanowires.

Metal−organic frameworks (MOF) have recently emerged as versatile precursors to fabricate functional MOF derivatives for oxygen evolution reactions (OER). Herein, we developed a controlled partial pyrolysis strategy to construct robust NiCo/Fe 3 O 4 heteroparticles within MOF-74 for efficient OER using trimetallic NiCoFe-MOF-74 as precursor. The partial pyrolysis method preserves the framework structure of MOF for effective substrates diffusion while producing highly active nanoparticles. The as-prepared NiCo/Fe 3 O 4 /MOF-74 delivered remarkably stable OER current with an overpotential as low as 238 mV at 10.0 mA cm −2 and an Tafel slop of 29 mV/dec, outperforming those of pristine NiCoFe-MOF-74, totally decomposed MOF derivatives, and most reported non-noble metal based electrocatalysts. The key for the formation of NiCo/Fe 3 O 4 /MOF-74 nanostructures is that the metals can be decomposed from NiCoFe-MOF-74 in the order of Ni, Co, and Fe under controlled heat treatment. Density functional theory calculations reveals that the underlying NiCo promotes the OER activity of Fe 3 O 4 through exchange stabilization of active oxygen species.

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It is highly desirable but challenging to optimize the structure of photocatalysts at the atomic scale to facilitate the separation of electron–hole pairs for enhanced performance. Now, a highly efficient photocatalyst is formed by assembling single Pt atoms on a defective TiO2 support (Pt1/def‐TiO2). Apart from being proton reduction sites, single Pt atoms promote the neighboring TiO2 units to generate surface oxygen vacancies and form a Pt‐O‐Ti3+ atomic interface. Experimental results and density functional theory calculations demonstrate that the Pt‐O‐Ti3+ atomic interface effectively facilitates photogenerated electrons to transfer from Ti3+ defective sites to single Pt atoms, thereby enhancing the separation of electron–hole pairs. This unique structure makes Pt1/def‐TiO2 exhibit a record‐level photocatalytic hydrogen production performance with an unexpectedly high turnover frequency of 51423 h−1, exceeding the Pt nanoparticle supported TiO2 catalyst by a factor of 591.

Methanol−water reforming is a promising solution for H 2 production/transportation in stationary and mobile hydrogen applications. Developing inexpensive catalysts with sufficiently high activity, selectivity, and stability remains challenging. In this paper, nickel-supported over face-centered cubic (fcc) phase α-MoC has been discovered to exhibit extraordinary hydrogen production activity in the aqueous-phase methanol reforming reaction. Under optimized condition, the hydrogen production rate of 2% Ni/α-MoC is about 6 times higher than that of conventional noble metal 2% Pt/Al 2 O 3 catalyst. We demonstrate that Ni is atomically dispersed over α-MoC via carbon bridge bonds, forming a Ni 1 −C x motif on the carbide surface. Such Ni 1 −C x motifs can effectively stabilize the isolated Ni 1 sites over the α-MoC substrate, rendering maximized active site density and high structural stability. In addition, the synergy between Ni 1 −C x motif and α-MoC produces an active interfacial structure for water dissociation, methanol activation, and successive reforming processes with compatible activity.

wileyonlinelibrary.comcathode materials with well-ordered structures where most of doping metal atoms exist in the transition-metal sublattice. However, the conventional layered oxide cathode after modifi cation can only deliver a practical capacity of less than 200 mAh g −1 .In recent years, lithium-rich layered oxides based on Li 2 MO 3 (M = Mn, Ru etc.) with layered structure are considered as promising cathodes for Li-ion batteries due to their higher capacity of more than 220 mAh g −1 and higher stability at high voltage as compared with the conventional LiMO 2 layered oxides, provoking worldwide attentions. [8][9][10][11][12][13][14] The common feature accounting for the high capacities of these lithium-rich layered oxides is the two redox processes involving both of cation and anion. [ 10,13,15,16 ] Despite the same process of partly charge compensation by oxygen during deep charging/discharging process, the lithiumrich layered oxides can deliver much higher reversible capacity than that of conventional cathode materials. To the best of our knowledge, such difference on the structural stability between the conventional and lithium-rich layered oxides has attracted limited attention. It is of high importance that there must be some unknown mechanism leading to the stability difference since the geometric and electronic structure between these two kinds of layered materials are similar, except for the superlattice structure. In present work, we elucidate why lithium-rich layered oxides Li 2 RuO 3 exhibit high capacities without undergoing a structural collapse for a certain number of cycles by tracking the electronic and geometric structural changes induced in Li 2 RuO 3 during charging/discharging. Backed up with the density functional theory (DFT) calculations and a series of in situ experiments, we unravel that the presence of the lithium atoms in the transition metal layer could make the lithium-rich structure fl exible, facilitating the formation of O 2 2− -like species, which favors the structural integrity and providing high capacity. Results and DiscussionWe chose Li 2 RuO 3 as the model lithium-rich compound because it contains a single metal, making it convenient to track the electronic and geometric structural changes during charging/discharging process without interference. In addition,

Although great progress has been made in artificial enzyme engineering, their catalytic performance is far from satisfactory as alternatives of natural enzymes. Here, we report a novel and efficient strategy to access high-performance nanozymes via direct atomization of platinum nanoparticles (Pt NPs) into single atoms by reversing the thermal sintering process. Atomization of Pt NPs into single atoms makes metal catalytic sites fully exposed and results in engineerable structural and electronic properties, thereby leading to dramatically enhanced enzymatic performance. As expected, the as-prepared thermally stable Pt single-atom nanozyme (PtTS-SAzyme) exhibited remarkable peroxidase-like catalytic activity and kinetics, far exceeding the Pt nanoparticle nanozyme. The following density functional theory calculations revealed that the engineered P and S atoms not only promote the atomization process from Pt NPs into PtTS-SAzyme but also endow single-atom Pt catalytic sites with a unique electronic structure owing to the electron donation of P atoms, as well as the electron acceptance of N and S atoms, which simultaneously contribute to the substantial enhancement of the enzyme-like catalytic performance of PtTS-SAzyme. This work demonstrates that thermal atomization of the metal nanoparticle-based nanozymes into single-atom nanozymes is an effective strategy for engineering high-performance nanozymes, which opens up a new way to rationally design and optimize artificial enzymes to mimic natural enzymes.