Abstract
Single-atom catalysts (SACs) are promising candidates to catalyze electrochemical CO
2
reduction (ECR) due to maximized atomic utilization. However, products are usually limited to CO ...instead of hydrocarbons or oxygenates due to unfavorable high energy barrier for further electron transfer on synthesized single atom catalytic sites. Here we report a novel partial-carbonization strategy to modify the electronic structures of center atoms on SACs for lowering the overall endothermic energy of key intermediates. A carbon-dots-based SAC margined with unique CuN
2
O
2
sites was synthesized for the first time. The introduction of oxygen ligands brings remarkably high Faradaic efficiency (78%) and selectivity (99% of ECR products) for electrochemical converting CO
2
to CH
4
with current density of 40 mA·cm
-2
in aqueous electrolytes, surpassing most reported SACs which stop at two-electron reduction. Theoretical calculations further revealed that the high selectivity and activity on CuN
2
O
2
active sites are due to the proper elevated CH
4
and H
2
energy barrier and fine-tuned electronic structure of Cu active sites.
Fluorine‐contained polymers, which have been widely used in highly efficient polymer solar cells (PSCs), are rather costly due to their complicated synthesis and low yields in the preparation of ...components. Here, the feasibility of replacing the critical fluorine substituents in high‐performance photovoltaic polymer donors with chlorine is demonstrated, and two polymeric donors, PBDB‐T‐2F and PBDB‐T‐2Cl, are synthesized and compared in parallel. The synthesis of PBDB‐T‐2Cl is much simpler than that of PBDB‐T‐2F. The two polymers have very similar optoelectronic and morphological properties, except the chlorinated polymer possess lower molecular energy levels than the fluorinated one. As a result, the PBDB‐T‐2Cl‐based PSCs exhibit higher open circuit voltage (Voc) than the PBDB‐T‐2F‐based devices, leading to an outstanding power conversion efficiency of over 14%. This work establishes a more economical design paradigm of replacing fluorine with chlorine for preparing highly efficient polymer donors.
A chlorinated polymer donor, PBDB‐T‐2Cl, is synthesized and compared in parallel with its fluorinated counterpart, PBDB‐T‐2F. PBDB‐T‐2Cl exhibits a much simpler synthesis route, which is favorable for future practical application of organic solar cells; in addition, a high power conversion efficiency of 14.4% (with certified PCE of 13.9% by the National Institute of Metrology) and good stability tested over 1000 h is achieved.
Electrochemical reduction of carbon dioxide (CO2) is an appealing approach toward tackling climate change associated with atmospheric CO2 emissions. This approach uses CO2 as the carbon feedstock to ...produce value‐added chemicals, resulting in a carbon‐neutral (or even carbon‐negative) process for chemical production. Many efforts have been devoted to the development of CO2 electrolysis devices that can be operated at industrially relevant rates; however, limited progress has been made, especially for valuable C2+ products. Herein, a nanoporous copper CO2 reduction catalyst is synthesized and integrated into a microfluidic CO2 flow cell electrolyzer. The CO2 electrolyzer exhibits a current density of 653 mA cm−2 with a C2+ product selectivity of ≈62% at an applied potential of −0.67 V (vs reversible hydrogen electrode). The highly porous electrode structure facilitates rapid gas transport across the electrode–electrolyte interface at high current densities. Further investigations on electrolyte effects reveal that the surface pH value is substantially different from the pH of bulk electrolyte, especially for nonbuffering near‐neutral electrolytes when operating at high currents.
A nanoporous copper catalyst for CO2 reduction is synthesized and integrated into a microfluidic CO2 flow cell electrolyzer with well‐engineered electrode–electrolyte interface. The CO2 electrolyzer exhibits a current density over 650 mA cm−2 with a C2+ product selectivity of ≈62% at a mild overpotential, which represents one of the highest performances that have been achieved to date.
We report a new strategy to prepare a composite catalyst for highly efficient electrochemical CO2 reduction reaction (CO2RR). The composite catalyst is made by anchoring Au nanoparticles on Cu ...nanowires via 4,4′‐bipyridine (bipy). The Au‐bipy‐Cu composite catalyzes the CO2RR in 0.1 m KHCO3 with a total Faradaic efficiency (FE) reaching 90.6 % at −0.9 V to provide C‐products, among which CH3CHO (25 % FE) dominates the liquid product (HCOO−, CH3CHO, and CH3COO−) distribution (75 %). The enhanced CO2RR catalysis demonstrated by Au‐bipy‐Cu originates from its synergistic Au (CO2 to CO) and Cu (CO to C‐products) catalysis which is further promoted by bipy. The Au‐bipy‐Cu composite represents a new catalyst system for effective CO2RR conversion to C‐products.
Joint action: Au nanoparticles were attached to Cu nanowires through a 4,4′‐bipyridine (bipy) linker to form the new composite catalyst Au‐bipy‐Cu. Thanks to the synergistic catalysis of Au (for CO2 to CO), Cu (for CO coupling), and bipy (for the CO2* stabilization and protonation), this catalyst demonstrates enhanced electrochemical reduction of CO2 to hydrocarbons.
The electroreduction of CO
is a promising technology for carbon utilization. Although electrolysis of CO
or CO
-derived CO can generate important industrial multicarbon feedstocks such as ethylene, ...ethanol, n-propanol and acetate, most efforts have been devoted to promoting C-C bond formation. Here, we demonstrate that C-N bonds can be formed through co-electrolysis of CO and NH
with acetamide selectivity of nearly 40% at industrially relevant reaction rates. Full-solvent quantum mechanical calculations show that acetamide forms through nucleophilic addition of NH
to a surface-bound ketene intermediate, a step that is in competition with OH
addition, which leads to acetate. The C-N formation mechanism was successfully extended to a series of amide products through amine nucleophilic attack on the ketene intermediate. This strategy enables us to form carbon-heteroatom bonds through the electroreduction of CO, expanding the scope of products available from CO
reduction.
Tumor hypoxia, the “Achilles’ heel” of current cancer therapies, is indispensable to drug resistance and poor therapeutic outcomes especially for radiotherapy. Here we propose an in situ catalytic ...oxygenation strategy in tumor using porphyrinic metal‐organic framework (MOF)‐gold nanoparticles (AuNPs) nanohybrid as a therapeutic platform to achieve O2‐evolving chemoradiotherapy. The AuNPs decorated on the surface of MOF effectively stabilize the nanocomposite and serve as radiosensitizers, whereas the MOF scaffold acts as a container to encapsulate chemotherapeutic drug doxorubicin. In vitro and in vivo studies verify that the catalase‐like nanohybrid significantly enhances the radiotherapy effect, alleviating tumor hypoxia and achieving synergistic anticancer efficacy. This hybrid nanomaterial remarkably suppresses the tumor growth with minimized systemic toxicity, opening new horizons for the next generation of theranostic nanomedicines.
A catalase‐like nanohybrid based on AuNPs/gold(III) porphyrinic metal‐organic frameworks is fabricated for O2 self‐supported chemoradiotherapy. Such an all‐in‐one nanohybrid holds advantages of modulating tumor hypoxia, amplifying radiation effect, regulating drug release and combining chemotherapy with radiotherapy, which will be a paradigm in O2‐elevated radiochemotherapy that offers a novel strategy in multimodal cancer therapy.
Practical applications of nanostructured materials have been largely limited by the difficulties in controllable and scaled-up synthesis, large-sized highly ordered self-assembly, and macroscopic ...processing of nanostructures. Hydroxyapatite (HAP), the major inorganic component of human bone and tooth, is an important biomaterial with high biocompatibility, bioactivity, and high thermal stability. Large-sized highly ordered HAP nanostructures are of great significance for applications in various fields and for understanding the formation mechanisms of bone and tooth. However, the synthesis of large-sized highly ordered HAP nanostructures remains a great challenge, especially for the preparation of large-sized highly ordered ultralong HAP nanowires because ultralong HAP nanowires are easily tangled and aggregated. Herein, we report our three main research findings: (1) the large-scale synthesis of highly flexible ultralong HAP nanowires with lengths up to >100 μm and aspect ratios up to >10000; (2) the demonstration of a strategy for the rapid automated production of highly flexible, fire-resistant, large-sized, self-assembled highly ordered ultralong HAP nanowires (SHOUHNs) at room temperature; and (3) the successful construction of various flexible fire-resistant HAP ordered architectures using the SHOUHNs, such as high-strength highly flexible nanostructured ropes (nanoropes), highly flexible textiles, and 3-D printed well-defined highly ordered patterns. The SHOUHNs are successively formed from the nanoscale to the microscale then to the macroscale, and the ordering direction of the ordered HAP structure is controllable. These ordered HAP architectures made from the SHOUHNs, such as highly flexible textiles, may be engineered into advanced functional products for applications in various fields, for example, fireproof clothing.
During photodynamic therapy (PDT), severe hypoxia often occurs as an undesirable limitation of PDT owing to the O2‐consuming photodynamic process, compromising the effectiveness of PDT. To overcome ...this problem, several strategies aiming to improve tumor oxygenation are developed. Unlike these traditional approaches, an opposite method combining hypoxia‐activated prodrug and PDT may provide a promising strategy for cancer synergistic therapy. In light of this, azido‐/photosensitizer‐terminated UiO‐66 nanoscale metal–organic frameworks (UiO‐66‐H/N3 NMOFs) which serve as nanocarriers for the bioreductive prodrug banoxantrone (AQ4N) are engineered. Owing to the effective shielding of the nanoparticles, the stability of AQ4N is well preserved, highlighting the vital function of the nanocarriers. By virtue of strain‐promoted azide–alkyne cycloaddition, the nanocarriers are further decorated with a dense PEG layer to enhance their dispersion in the physiological environment and improve their therapeutic performance. Both in vitro and in vivo studies reveal that the O2‐depleting PDT process indeed aggravates intracellular/tumor hypoxia that activates the cytotoxicity of AQ4N through a cascade process, consequently achieving PDT‐induced and hypoxia‐activated synergistic therapy. Benefiting from the localized therapeutic effect of PDT and hypoxia‐activated cytotoxicity of AQ4N, this hybrid nanomedicine exhibits enhanced therapeutic efficacy with negligible systemic toxicity, making it a promising candidate for cancer therapy.
Nanoscale metal–organic frameworks‐based nanohybrids capable of protecting prodrugs from degradation are engineered for photodynamic therapy and hypoxia‐triggered cascade chemotherapy. The nanovehicles with good stability, favorable photodynamic therapy (PDT) performance, and on‐demand prodrug release take advantage of the hypoxia generated by PDT to activate cascade chemotherapy, achieving enhanced tumor suppression as well as negligible systemic toxicity.
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