A series of stable heterometallic Fe2M cluster‐based MOFs (NNU‐31‐M, M=Co, Ni, Zn) photocatalysts are presented. They can achieve the overall conversion of CO2 and H2O into HCOOH and O2 without the ...assistance of additional sacrificial agent and photosensitizer. The heterometallic cluster units and photosensitive ligands excited by visible light generate separated electrons and holes. Then, low‐valent metal M accepts electrons to reduce CO2, and high‐valent Fe uses holes to oxidize H2O. This is the first MOF photocatalyst system to finish artificial photosynthetic full reaction. It is noted that NNU‐31‐Zn exhibits the highest HCOOH yield of 26.3 μmol g−1 h−1 (selectivity of ca. 100 %). Furthermore, the DFT calculations based on crystal structures demonstrate the photocatalytic reaction mechanism. This work proposes a new strategy for how to design crystalline photocatalyst to realize artificial photosynthetic overall reaction.
A series of stable heterometallic Fe2M cluster‐based MOFs achieve the overall conversion of CO2 and H2O into HCOOH and O2 without the assistance of additional sacrificial agent and photosensitizer. A strategy is proposed to design crystalline photocatalysts to realize the overall artificial photosynthetic reaction.
The photocatalytic reduction of CO2 to energy carriers has emerged as one of the most promising strategies to alleviate the energy crisis and CO2 pollution, for which the development of catalyst was ...considered as the determining factor for the accomplishment of this conversion process. In this study, three stable and isostructural metal–organic frameworks (denoted as MOF-Ni, MOF-Co, and MOF-Cu) have been synthesized and used as heterogeneous catalysts in photocatalytic CO2 reduction reaction (CO2RR). It is worth noting that the MOF-Ni exhibited very high selectivity of 97.7% for photoreducing CO2 to CO, which has exceeded most of the reported MOF-based catalysts in the field. Significantly, the MOFs associated with a monometallic catalytic center offer a simple and precise structural model which allows us to understand more definitively the specific effects of different metal-ion species on photoreduction of CO2 as well as the reactive mechanism.
Abstract
The electrochemical CO
2
reduction to high-value-added chemicals is one of the most promising and challenging research in the energy conversion field. An efficient ECR catalyst based on a ...Cu-based conductive metal-organic framework (Cu-DBC) is dedicated to producing CH
4
with superior activity and selectivity, showing a Faradaic efficiency of CH
4
as high as ~80% and a large current density of −203 mA cm
−2
at −0.9 V vs. RHE. The further investigation based on theoretical calculations and experimental results indicates the Cu-DBC with oxygen-coordinated Cu sites exhibits higher selectivity and activity over the other two crystalline ECR catalysts with nitrogen-coordinated Cu sites due to the lower energy barriers of Cu-O
4
sites during ECR process. This work unravels the strong dependence of ECR selectivity on the Cu site coordination environment in crystalline porous catalysts, and provides a platform for constructing highly selective ECR catalysts.
Over the past 200 years, the most famous and important heteroatom Keggin architecture in polyoxometalates has only been synthesized with Mo, W, V, or Nb. Now, the self‐assembly of two phosphate ...(PO43−)‐centered polyoxo‐titanium clusters (PTCs) is presented, PTi16 and PTi12, which display classic heteroatom Keggin and its trivacant structures, respectively. Because TiIV has lower oxidate state and larger ionic radius than MoVI, WVI, VV, and NbV, additional TiIV centres in these PTCs are used to stabilize the resultant heteroatom Keggin structures, as demonstrated by the cooresponding theoretical calculation results. These photoactive PTCs can be utilized as efficient photocatalysts for highly selective CO2‐to‐HCOOH conversion. This new discovery indicates that the classic heteroatom Keggin family can be assembled with Ti, thus opening a research avenue for the development of PTC chemistry.
One of the family: A TiIV‐based heteroatom Keggin and its trivacant lacunary architectures were structurally synthesized as a polyoxo‐titanium cluster. They exhibited a very high selectivity and activity for photocatalytic CO2‐to‐HCOOH conversion.
2D nanomaterials with flexibly modifiable surfaces are highly sought after for various applications, especially in room‐temperature chemiresistive gas sensing. Here, we have prepared a series of COF ...2D nanomaterials (porphyrin‐based COF nanosheets (NS)) that enabled highly sensitive and specific‐sensing of NO2 at room temperature. Different from the traditional 2D sensing materials, H2‐TPCOF was designed with a largely reduced interlayer interaction and predesigned porphyrin rings as modifiable sites on its surfaces for post‐metallization. After post‐metallization, the metallized M‐TPCOF (M=Co and Cu) showed remarkably improved sensing performances. Among them, Co‐TPCOF exhibited highly specific sensing toward NO2 with one of the highest sensitivities of all reported 2D materials and COF materials, with an ultra‐low limit‐of‐detection of 6.8 ppb and fast response/recovery. This work might shed light on designing and preparing a new type of surface‐highly‐modifiable 2D material for various chemistry applications.
A series of metalloporphyrin covalent organic framework based nanosheets has been synthesized and successfully applied in specific sensing of NO2 at room temperature.
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•We identified 8 MVI preoperative risk factors in HCC, including radiomic features.•Radiomic features do not provide significant added value to radiologist scores.•A model integrating ...clinic-radiologic and radiomic features demonstrates good performance for predicting MVI.
Microvascular invasion (MVI) impairs surgical outcomes in patients with hepatocellular carcinoma (HCC). As there is no single highly reliable factor to preoperatively predict MVI, we developed a computational approach integrating large-scale clinical and imaging modalities, especially radiomic features from contrast-enhanced CT, to predict MVI and clinical outcomes in patients with HCC.
In total, 495 surgically resected patients were retrospectively included. MVI-related radiomic scores (R-scores) were built from 7,260 radiomic features in 6 target volumes. Six R-scores, 15 clinical factors, and 12 radiographic scores were integrated into a predictive model, the radiographic-radiomic (RR) model, with multivariate logistic regression.
Radiomics related to tumor size and intratumoral heterogeneity were the top-ranked MVI predicting features. The related R-scores showed significant differences according to MVI status (p <0.001). Regression analysis identified 8 MVI risk factors, including 5 radiographic features and an R-score. The R-score (odds ratio OR 2.34) was less important than tumor capsule (OR 5.12), tumor margin (OR4.20), and peritumoral enhancement (OR 3.03). The RR model using these predictors achieved an area under the curve (AUC) of 0.909 in training/validation and 0.889 in the test set. Progression-free survival (PFS) and overall survival (OS) were significantly different between the RR-predicted MVI-absent and MVI-present groups (median PFS: 49.5 vs. 12.9 months; median OS: 76.3 vs. 47.3 months). RR-computed MVI probability, histologic MVI, tumor size, and Edmondson-Steiner grade were independently associated with disease-specific recurrence and mortality.
The computational approach, integrating large-scale clinico-radiologic and radiomic features, demonstrates good performance for predicting MVI and clinical outcomes. However, radiomics with current CT imaging analysis protocols do not provide statistically significant added value to radiographic scores.
The most effective treatment for hepatocellular carcinoma (HCC) is surgical removal of the tumor but often recurrence occurs, partly due to the presence of microvascular invasion (MVI). Lacking a single highly reliable factor able to preoperatively predict MVI, we developed a computational approach to predict MVI and the long-term clinical outcome of patients with HCC. In particular, the added value of radiomics, a newly emerging form of radiography, was comprehensively investigated. This computational method can enhance the communication with the patient about the likely success of the treatment and guide clinical management, with the aim of finding drugs that reduce the risk of recurrence.
Despite wide applications of bimetallic electrocatalysis in oxygen evolution reaction (OER) owing to their superior performance, the origin of the improved performance remains elusive. The underlying ...mechanism was explored by designing and synthesizing a series of stable metal–organic frameworks (MOFs: NNU‐21–24) based on trinuclear metal carboxylate clusters and tridentate carboxylate ligands. Among the examined stable MOFs, NNU‐23 exhibits the best OER performance; particularly, compared with monometallic MOFs, all the bimetallic MOFs display improved OER activity. DFT calculations and experimental results demonstrate that introduction of the second metal atom can improve the activity of the original atom. The proposed model of bimetallic electrocatalysts affecting their OER performance can facilitate design of efficient bimetallic catalysts for energy storage and conversion, and investigation of the related catalytic mechanisms.
An iron atom in an Fe3 cluster is replaced by a second metal to form Fe2M clusters, which can serve as nodes to bridge with organic ligands and construct stable bimetallic MOFs. The introduction of the second metal atom can improve the activity of the original atom and thus improve the oxygen evolution reaction performance of electrocatalysts.
Artificial photosynthetic diluted CO2 reduction directly driven by natural sunlight is a challenging, but promising way to realize carbon‐resources recycling utilization. Herein, a three‐in‐one ...photocatalytic system of CO2 enrichment, CO2 reduction and H2O oxidation sites is designed for diluted CO2 reduction. A Zn‐Salen‐based covalent organic framework (Zn‐S‐COF) with oxidation and reductive sites is synthesized; then, ionic liquids (ILs) are loaded into the pores. As a result, EmimBF4@Zn‐S‐COF shows a visible‐light‐driven CO2‐to‐CO conversion rate of 105.88 µmol g−1 h−1 under diluted CO2 (15%) atmosphere, even superior than most photocatalysts in high concentrations CO2. Moreover, natural sunlight driven diluted CO2 reduction rate also reaches 126.51 µmol g−1 in 5 h. Further experiments and theoretical calculations reveal that the triazine ring in the Zn‐S‐COF promotes the activity of H2O oxidation and CO2 reduction sites, and the loaded ILs provide an enriched CO2 atmosphere, realizing the efficient photocatalytic activity in diluted CO2 reduction.
Although photocatalytic C−H activation has been realized by using heterogeneous catalysts, most of them require high‐temperature conditions to provide the energy required for C−H bond breakage. The ...catalysts with photothermal conversion properties can catalyze this reaction efficiently at room temperature, but so far, these catalysts have been rarely developed. Here, we construct bifunctional catalysts Rh‐COF‐316 and ‐318 to combine photosensitive covalent organic frameworks (COFs) and transition‐metal catalytic moiety using a post‐synthetic approach. The Rh‐COF enable the heterogeneous C−H activation reaction by photothermal conversion for the first time, and exhibit excellent yields (up to 98 %) and broad scope of substrates in 4+2 annulation at room temperature, while maintaining the high stability and recyclability. Significantly, this work is the highest yield reported so far in porous materials catalyzing C(sp2)−C(sp2) formation at room temperature. The excellent performances can be attributed to the COF‐316, which enhances the photothermal effect (ΔT=50.9 °C), thus accelerating C−H bond activation and the exchange of catalyst with substrates.
In this work, a general post‐synthetic strategy for constructing bifunctional catalysts, Rh‐COF, which connect photosensitive covalent organic frameworks and transition‐metal catalytic groups through covalent bonding, was developed. Fascinatingly, such complexes enable efficient photothermal conversion properties, which can improve the photothermal catalytic performances in C−H activation to obtain excellent yield, substrate suitability and recyclability.
The exploration of new application forms of covalent organic frameworks (COFs) in Li−S batteries that can overcome drawbacks like low conductivity or high loading when typically applied as sulfur ...host materials (mostly ≈20 to ≈40 wt % loading in cathode) is desirable to maximize their low‐density advantage to obtain lightweight, portable, or high‐energy‐density devices. Here, we establish that COFs could have implications as microadditives of binders (≈1 wt % in cathode), and a series of anthraquinone‐COF based hollow tubes have been prepared as model microadditives. The microadditives can strengthen the basic properties of the binder and spontaneously immobilize and catalytically convert lithium polysulfides, as proved by density functional calculations, thus showing almost doubly enhanced reversible capacity compared with that of the bare electrode.
Covalent organic frameworks could have implications as microadditives of binders (≈1 wt % in cathode) and a series of anthraquinone‐COF based hollow tubes have been prepared as model microadditives to obtain a high‐performance binder in Li−S batteries.
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