Zhao-Di Zhou, Zi-Long Xu, Dan Wang, Lin-Fang Jia, Han-Qing Zhao, Bao-Yi Yu* and Chong-Chen Wang*
The demon mirror (Zhaoyaojing in Chinese) in the
Journey to the West, a Chinese classical literature, can reflect the original
shape of demons. Both as-prepared coordination polymers, [Zn(PTA)(DTP)(H2O)2]·(DMF)(CP-1) and [Zn(BTC)(DTP)]·(CH3CN)1.5·(H2O)4 (CP-2), can act as demon
mirror to detect the different environmental pollutants. This image presented
the magic demon mirror to reflect the presence of pollutants, the demons in
environment, which provided an opportunity for the readers to appreciate Chinese
traditional culture.
Endohedral metallofullerenes (EMFs) exhibit various properties due to
their multiple combinations between internal metals and outer carbon cages.
Among them, yttrium-based metallofullerenes have attracted much attention due
to their luminescence properties. For example, Y3N@C80 is
distinguished by its photoluminescence (PL) properties with a small energy gap
between the lowest singlet states (S1) and the triplet excited
states (T1) in Y3N@C80, allowing reverse intersystem crossing (RISC) of T1→S1 and resulting in thermally
activated delayed fluorescence (TADF). In addition, the PL intensity, lifetime,
and quantum yield (QY) of Y3N@C80 all depend on the
molecular structure and surrounding environment. Typically, modulation of the
PL properties can be achieved by replacing the yttrium metal inside the carbon
cage as well as by modifying the carbon cage externally. Here, we focus on the
luminescence properties of yttrium-based metallofullerenes, summarize recent
research advances, and predict their future development.
Electrocatalytic water splitting to produce hydrogen is an eco-friendly way to achieve sustainable utilization of renewable energy. The industrial application of water electrolysis, which is severely limited by slow kinetic reactions on electrode surfaces, requires the development of highly reactive, low-cost and stable electrocatalytic materials. Transition metal borides/borates have recently emerged as promising electrocatalytic materials for catalyzing hydrogen/oxygen evolution reactions (HER/OER) in inexpensive electrolyzers. However, so far, there has been little comprehensive summary of transition metal borides/borates. Here, this review provides the latest research progress on transition metal borides/borates for electrocatalytic water splitting. The structural characteristics of transition metal borides/borates and their synthesis methods in recent years are discussed. Then, the theoretical and experimental progress of transition metal borides including single-metal borides, multi-metal borides, borate derived and other nanocomposites containing boron (boron-doped nanocomposites/substrate with boron) in electrocatalytic reaction and the role of boron in regulating electrocatalytic performance are further emphasized. Finally, the potential challenges and future prospects of transition metal borides/borates in electrocatalysis are presented.
Li-rich
manganese-based cathode materials (LR) are considered as excellent cathode materials for a new generation of
lithium-ion batteries causes their outstanding electrochemical
performance, friendly price, and environmental friendliness. But defects such
as rapid voltage decay and loss of lattice oxygen limit their applications. The
electrochemical performance of LR has to be improved by means of modification.
The previous single modification methods like element doping, surface coating,
structure design, etc. can only optimize the electrochemical performance of LR
from one aspect. Recently, multiple modifications, which can combine the
advantages of multiple modifications, have been favored by researchers. Here,
we comprehensively review the recent progress of multiple modification of LR
based on the combination of different modification means. The review and
summary of the multiple modification of LR will play a guiding role in its
development in the future.
Polymer-inorganic (P-I) soft-hard heterostructures & heterojunction photocatalysts, featured by large interfacial contact, efficient charge separation, broad light absorption and maximized redox capacity, have received great attention for their applications in environmental remediation and energy conversion. In this minireview, the classification and mechanism of P-I heterojunctions, i.e., type-I/II, p-n, Z-scheme and S-scheme heterojunctions, and their preparation methods are firstly introduced. Next, the photocatalytic applications of P-I heterojunctions, including water splitting, environmental remediation and carbon dioxide reduction, are extensively reviewed. Lastly, a brief summary and perspectives on ongoing challenges and opportunities to construct high performance P-I soft-hard photocatalysts are intensively highlighted. We envision this review will provide a picture of the state-of-the-art achievements and promote the photocatalytic applications of P-I heterostructures in energy conversion and environmental remediation.
Photocatalytic
mineralization of recalcitrant contaminants like phenol in wastewater requires
abundant hydroxyl radicals (·OH) to initiate the reaction prior to the
ring-opening. We here increase the free energy for adsorption of O* species on TiO2 surface and slightly downshift the band position by
tin doping. This can simultaneously promote
the generation and suppress the annihilation of ·OH. Besides, tin doping can
also facilitate semiconductor-cocatalyst-solution
(SCS) interfacial electron transfer by lowering the potential barrier and
synergistically enhance the photon utilization. By filming the photocatalyst
onto our developed fixed bed reactors, the loss of photons resulting from
undesirable absorption by contaminants can be alleviated. By these virtues,
trace amount of phenol in wastewater can be efficiently mineralized.
Metal-organic frameworks with chiral feature
(chirMOFs) are attracting great attention on circularly polarized luminescence
(CPL). However, developing new efficient strategy to achieve or improve CPL
properties is an urgent task. Herein, new chiral MOF thin films prepared by
liquid-phase epitaxial layer by layer (lbl) growth method (SURchirMOF) are
composed of D- or L-camphorate (D/Lcam) and aminopyrazine (Pr-NH2)
by using liquid phase epitaxial layer by layer (lbl) method. The resulted Zn2(D/Lcam)2Pr-NH2 SURchirMOF shows strong chirality and luminescence but weak CPL emission at 390
nm. After lbl modifying a dye molecule FluoresceinIsothiocyanate (FITC), the
chiroptical Zn2(D/Lcam)2Pr-NH-FITC SURchirMOFs with ~7
times CPL signal improvement and ~3 times glum value
amplification are obtained. This work provides a new strategy to develop chiral
MOF thin films for CPL improvement using lbl grafting approach.
Although
Pt-based catalysts have been considered as the most effective electrocatalyst
for the cathodic oxygen reduction reaction (ORR) of direct methanol fuel cells
(DMFCs), they still suffer from the drawbacks of high cost, poor long-term
stability and methanol/ CO poisoning effects. Thus, developing low-cost ORR
catalysts with high efficiency, durability and antipoisoning ability is of
paramount importance. Herein, a series of
non-noble metal FeNC materials are prepared through a facile pyrolysis process
and used as the electrocatalysts toward ORR in alkaline electrolyte. Results
show that the Fe0.50NC-800-1h catalyst pyrolyzed at 800 ºC for 1 h
with the mass ratio of Fe(NO3)3·6H2O
to melamine being 0.50 exhibits the highest catalytic performance among
the as-prepared FeNC catalysts. The half-wave potential of ORR is ca. 0.81 V, which is only 38 mV lower
than that on the noble metal Pt/C catalyst. Besides, it also displays higher
stability and methanol tolerance than Pt/C. There is almost no change in the
current during the chronoamperometric
test when methanol is added in
the electrolyte whereas significant decrease is found on Pt/C catalyst. This
study of FeNC catalysts
provides new insights on understanding the ORR mechanism and suggests a
promising strategy to develop low-cost and highly efficient non-noble
metal electrocatalysts for ORR.
Two
coordination polymers (CPs) [Zn(PTA)(DTP)(H2O)2]·(DMF)(CP-1) and [Zn(BTC)(DTP)]·(CH3CN)1.5·(H2O)4 (CP-2) with one- and two-dimensional architectures were
synthesized from Zn(II) ion and different organic linkers like terephthalic acid (H2PTA),
benzene-1,3,5-tricarboxylic acid (H3BTC), and 3,5-di(1,2,4-triazol-1-yl) pyridine (DTP). The
fluorescent sensing experiments showed that the two CPs displayed effective,
sensitive, and selective abilities towards Fe3+ and Cr2O72-.
For sensing the pesticides, CP-1 outperforms in sensing of metamitron
(MMT) and CP-2 is
ultrasensitive towards imidacloprid (IMI). The possible mechanisms involved in
the quenching of the fluorescence intensity
include the inner filter effect (IFE) and the fluore- scence resonance energy transfer (FRET) effect.
In this work, the catalytic activities of Mo2C-MXene for the co-synthesis of urea from N2 and CO2 are reported by well-defined
density functional theory (DFT) method. The calculated results show that the
presence of surface functional groups is not conducive to the CO2/N2 (C/N) coupling process in urea synthesis reaction. The exposed Mo2C
on the surface can realize urea synthesis at the limit point of 0.69 eV, but
the large transition state energy barrier (1.50 eV) indicates that bare Mo2C is not a promising urea catalyst.
Loading single atoms can improve the urea synthesis performance of bare Mo2C.
The energy barrier of urea synthesis reaction and the transition state energy
barrier of C/N coupling reaction have dropped significantly by the atomic
loading of Fe and Ti on bare Mo2C. Moreover, Ti doped Mo2C
exhibits better catalytic selectivity toward urea production, making it an
excellent catalyst for urea synthesis. We hope this work can pave the way for
the electrochemical synthesis of urea.
Spatially isolated oxidation and reduction cocatalysts on a
semiconductor can realize efficient charge separation and thereby lead to
increased photocatalytic hydrogen
generation. However, the effective preparation of such photocatalysts
has proven challenging. Herein, we report the facile synthesis of a novel
noble-metal-free CdS/MoS2/CoPi ternary photocatalyst via a visible
light-induced synthesis route, in which MoS2 reduction cocatalysts
were precisely grown on the two terminals of CdS nanorods, while CoPi oxidation
cocatalysts were preferentially anchored onto the sidewalls of CdS nanorods.
Such spatially isolated MoS2 and CoPi redox cocatalysts endow CdS
nanorods with a rapid charge separation, which enhances their hydrogen generation
activity. The CdS/MoS2/CoPi photocatalyst with optimized CoPi amount
achieves the highest H2 generation rate of 206 μmol/h, which is 21 and 2 times higher than that achieved by using CdS
alone (9.7 μmol/h) and CdS/MoS2 (105 μmol/h), respectively. The present
work highlights the effectiveness of the spatial isolation of reduction and
oxidation sites for efficient charge separation and thereby provides a
promising strategy for the preparation of highly active photocatalysts.