Efficient conversion of carbon dioxide (CO2) into value-added products is essential for clean energy research. Design of stable, selective, and powerful electrocatalysts for CO2 reduction reaction (CO2RR) is highly desirable yet largely unmet. In this work, a series of metalloporphyrin-tetrathiafulvalene based covalent organic frameworks (M-TTCOFs) are designed. Tetrathiafulvalene, serving as electron donator or carrier, can construct an oriented electron transmission pathway with metalloporphyrin. Thus-obtained M-TTCOFs can serve as electrocatalysts with high FECO (91.3%, −0.7 V) and possess high cycling stability (>40 h). In addition, after exfoliation, the FECO value of Co-TTCOF nanosheets (~5 nm) is higher than 90% in a wide potential range from −0.6 to −0.9 V and the maximum FECO can reach up to almost 100% (99.7%, −0.8 V). The electrocatalytic CO2RR mechanisms are discussed and revealed by density functional theory calculations. This work paves a new way in exploring porous crystalline materials in electrocatalytic CO2RR.
In this work, we rationally designed a series of crystalline and stable dioxin‐linked metallophthalocyanine covalent organic frameworks (COFs; MPc‐TFPN COF, M=Ni, Co, Zn) under the guidance of reticular chemistry. As a novel single‐site catalysts (SSCs), NiPc/CoPc‐TFPN COF exhibited outstanding activity and selectivity for electrocatalytic CO2 reduction (ECR; Faradaic efficiency of CO (FECO)=99.8(±1.24) %/ 96.1(±1.25) % for NiPc/CoPc‐TFPN COF). More importantly, when coupled with light, the FECO and current density (jCO) were further improved across the applied potential range (−0.6 to −1.2 V vs. RHE) compared to the dark environment for NiPc‐TFPN COF (jCO increased from 14.1 to 17.5 A g−1 at −0.9 V; FECO reached up to ca. 100 % at −0.8 to −0.9 V). Furthermore, an in‐depth mechanism study was established by density functional theory (DFT) simulation and experimental characterization. For the first time, this work explored the application of COFs as photo‐coupled electrocatalysts to improve ECR efficiency, which showed the potential of using light‐sensitive COFs in the field of electrocatalysis.
Two novel isostructural polyoxometalate (POM)-based metal-organic frameworks (MOFs) with diamond topology, NENU-506 and NENU-507, were hydrothermally synthesized. They not only combine the advantages of both POMs and MOFs, but also show excellent chemical and thermal stability. Notably, NENU-507 exhibited a high reversible capacity of 640 mA h g after 100 cycles when applied as an anode material in lithium-ion batteries.
The
design of a powerful heterojunction
structure and the study
of the interfacial charge migration pathway at the atomic level are
essential to mitigate the photocorrosion and recombination of electron–hole
pairs of CdS in photocatalytic hydrogen evolution (PHE). A temperature-induced
self-assembly strategy has been proposed for the syntheses of Prussian
blue analogue (PBA)/CdS nanocomposites with beaded structure. The
specially designed structure had evenly exposed CdS which can efficiently
harvest visible light and inhibit photocorrosion; meanwhile, PBA with
a large cavity provided channels for mass transfer and photocatalytic
reaction centers. Remarkably, PB-Co/CdS-LT-3 exhibits a PHE rate of
57 228 μmol h
–1
g
–1
, far exceeding that of CdS or PB-Co and comparable to those of most
reported crystalline porous material-based photocatalysts. The high
performances are associated with efficient charge migration from CdS
to PB-Co through CN-Cd electron bridges, as revealed by the DFT calculations.
This work sheds light on the exploration of heterostructure materials
in efficient PHE.
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