Ruohong Shi

Co3ZnC/Co nano heterojunctions encapsulated in N-doped graphene layers derived from PBAs as highly efficient bi-functional OER and ORR electrocatalysts

The oxygen evolution reaction (OER) is a key half reaction involved in electrochemical water splitting. However, it is kinetically not favored and hence requires highly active electrocatalysts. Non-precious metal based catalysts have emerged as the most promising materials for the replacement of state-of-the-art noble metal catalysts. However, more progress is still needed to improve the activity and stability of these catalysts. Herein, we synthesized Co3ZnC/Co nanojunctions encapsulated in highly nitrogen doped graphene layers by one-step annealing of Prussian blue analogues (PBA). The catalyst shows a low overpotential of only 366 mV at 10 mA cm−2, which is superior to state-of-the-art commercial RuO2 catalysts. Besides, it exhibits a better performance compared with similar metallic carbide-based catalysts towards ORR with an onset potential and cathodic peak potential at 0.912 V and 0.814 V, respectively.

Active and Durable Hydrogen Evolution Reaction Catalyst Derived from Pd-Doped Metal–Organic Frameworks

The water electrolysis is of critical importance for sustainable hydrogen production. In this work, a highly efficient and stable PdCo alloy catalyst (PdCo@CN) was synthesized by direct annealing of Pd-doped metal-organic frameworks (MOFs) under N2 atmosphere. In 0.5 M H2SO4 solution, PdCo@CN displays remarkable electrocatalytic performance with overpotential of 80 mV, a Tafel slope of 31 mV dec(-1), and excellent stability of 10 000 cycles. Our studies reveal that noble metal doped MOFs are ideal precursors for preparing highly active alloy electrocatalysts with low content of noble metal.

Fe3O4@carbon@zeolitic imidazolate framework-8 nanoparticles as multifunctional pH-responsive drug delivery vehicles for tumor therapy in vivo

Controlled drug release is a promising approach for cancer therapy due to its merits of reduced systemic toxicity and enhanced antitumor efficacy. Here, multifunctional Fe3O4@carbon@zeolitic imidazolate framework-8 (FCZ) hybrid nanoparticles (NPs) were successfully constructed. Owing to the porosity and acid-sensitivity of zeolitic imidazolate framework-8 (ZIF-8), FCZ NPs not only displayed an improved drug loading capacity compared to most of the polymeric nanocarriers, but also exhibited excellent pH-triggered release of doxorubicin (DOX) in vitro. Moreover, carbon dots (CDs) embedded in the porous carbon shell and superparamagnetic iron oxide nanocrystals could simultaneously function as intracellular fluorescence imaging and T2*-weighted magnetic resonance imaging (MRI) contrast agents, respectively. The results obtained from the MTT assay demonstrated good biocompatibility of FCZ NPs. DOX release experiments showed pH regulation-dominated drug release kinetics: a weak acidic pH in tumor areas could trigger sustained drug release, suggesting that FCZ NPs are ideal drug delivery systems. Moreover, the remarkable inhibition of tumor growth without side effects was confirmed in vivo. These results provide convincing evidence establishing the multifunctional FCZ NPs as promising candidates for tumor therapy.

Pt-like electrocatalytic behavior of Ru–MoO2 nanocomposites for the hydrogen evolution reaction

The design and development of inexpensive highly efficient electrocatalysts are critically important for their practical applications in the hydrogen evolution reaction (HER). Plain Ru and MoO2 are not very active for the HER under alkaline conditions. In this work, we report the preparation of Ru–MoO2 nanocomposites via a facile in situ carburization of a Ru modified Mo-based metal–organic framework. The nanocomposites exhibited very low overpotential and superior stability to achieve 10 mA cm−2 under both acidic and alkaline conditions (55 mV in 0.5 M H2SO4 and 29 mV in 1 M KOH). Their excellent performance under alkaline conditions was even better than that of 20% Pt/C. Our experimental and computational (DFT) results reveal that the remarkable activity stems from the synergistic interplay produced by strong electronic interactions between MoO2 and Ru nanoparticles. This modulated electronic structure accompanying enhanced electrical conductivity would significantly improve the catalytic activity. This strategy provides an insight into the design and synthesis of a low-cost and high performance alternative to Pt-based catalysts for the HER.

Biodegradable Core-shell Dual-Metal-Organic-Frameworks Nanotheranostic Agent for Multiple Imaging Guided Combination Cancer Therapy

Metal-organic-frameworks (MOFs) possess high porosity, large surface area, and tunable functionality are promising candidates for synchronous diagnosis and therapy in cancer treatment. Although large number of MOFs has been discovered, conventional MOF-based nanoplatforms are mainly limited to the sole MOF source with sole functionality. In this study, surfactant modified Prussian blue (PB) core coated by compact ZIF-8 shell (core-shell dual-MOFs, CSD-MOFs) has been reported through a versatile stepwise approach. With Prussian blue as core, CSD-MOFs are able to serve as both magnetic resonance imaging (MRI) and fluorescence optical imaging (FOI) agents. We show that CSD-MOFs crystals loading the anticancer drug doxorubicin (DOX) are efficient pH and near-infrared (NIR) dual-stimuli responsive drug delivery vehicles. After the degradation of ZIF-8, simultaneous NIR irradiation to the inner PB MOFs continuously generate heat that kill cancer cells. Their efficacy on HeLa cancer cell lines is higher compared with the respective single treatment modality, achieving synergistic chemo-thermal therapy efficacy. In vivo results indicate that the anti-tumor efficacy of CSD-MOFs@DOX+NIR was 7.16 and 5.07 times enhanced compared to single chemo-therapy and single thermal-therapy respectively. Our strategy opens new possibilities to construct multifunctional theranostic systems through integration of two different MOFs.

Rapid Adsorption Enables Interface Engineering of PdMnCo Alloy/Nitrogen-Doped Carbon as Highly Efficient Electrocatalysts for Hydrogen Evolution Reaction

The catalytic performance of Pd-based catalysts has long been hindered by surface contamination, particle agglomeration, and lack of rational structural design. Here we report a simple adsorption method for rapid synthesis (∼90 s) of structure-optimized Pd alloy supported on nitrogen-doped carbon without the use of surfactants or extra reducing agents. The material shows much lower overpotential than 30 wt % Pd/C and 40 wt % Pt/C catalysts while exhibiting excellent durability (80 h). Moreover, unveiled by the density functional theory (DFT) calculation results, the underlying reason for the outstanding performance is that the PdMnCo alloy/pyridinic nitrogen-doped carbon interfaces weaken the hydrogen-adsorption energy on the catalyst and thus optimize the Gibbs free energy of the intermediate state (ΔGH*), leading to a remarkable electrocatalytic activity. This work also opens up an avenue for quick synthesis of a highly efficient structure-optimized Pd-based catalyst.

Photo-Enhanced Singlet Oxygen Generation of Prussian Blue-based Nanocatalyst for Imaging-Guided Augmented Photodynamic Therapy

Summary Therapeutic effects of photodynamic therapy (PDT) remain largely limited because of tumor hypoxia. Herein, we report safe and versatile nanocatalysts (NCs) for endogenous oxygen generation and imaging-guided enhanced PDT. The NCs (named as PSP) are prepared by coating Prussian blue (PB) with mesoporous silica to load photosensitizer (zinc phthalocyanine, ZnPc), followed by the modification of polyethylene glycol chains. The inner PB not only acts like a catalase for hydrogen peroxide decomposition but also serves as a photothermal agent to increase the local temperature and then speed up the oxygen supply under near-infrared irradiation. The loaded ZnPc can immediately transform the formed oxygen to generate cytotoxic singlet oxygen upon the same laser irradiation due to the overlapped absorption between PB and ZnPc. Results indicate that the PSP-ZnPc (PSPZP) NCs could realize the photothermally controlled improvement of hypoxic condition in cancer cells and tumor tissues, therefore demonstrating enhanced cancer therapy by the incorporation of PDT and photothermal therapy.

In Situ One-Pot Synthesis of MOF-Polydopamine Hybrid Nanogels with Enhanced Photothermal Effect for Targeted Cancer Therapy

Abstract Herein, a simple one‐pot way is designed to prepare a type of multifunctional metal–organic framework (MOF)‐based hybrid nanogels by in situ hybridization of dopamine monomer in the skeleton of MnCo. The resultant hybrid nanoparticles (named as MCP) show enhanced photothermal conversion efficiency in comparison with pure polydopamine or MnCo nanoparticles (NPs) synthesized under a similar method and, therefore, show great potential for photothermal therapy (PTT) in vivo. The MCP NPs are expected to possess T 1 positive magnetic resonance imaging ability due to the high‐spin Mn‐N6 (S = 5/2) in the skeleton of MnCo. To improve the therapy efficiency as a PTT agent, the MCP NPs are further modified with functional polyethylene glycol (PEG) and thiol terminal cyclic arginine–glycine–aspartic acid peptide, respectively: the first one is to increase the stability, biocompatibility, and blood circulation time of MCP NPs in vivo; the second one is to increase the tumor accumulation of MCP‐PEG NPs and improve their therapeutic efficiency as photothermal agent.