Abstract
Ascertaining the function of in-plane intrinsic defects and edge atoms is necessary for developing efficient low-dimensional photocatalysts. We report the wireless photocatalytic CO
2
...reduction to CH
4
over reconstructed edge atoms of monolayer 2H-WSe
2
artificial leaves. Our first-principles calculations demonstrate that reconstructed and imperfect edge configurations enable CO
2
binding to form linear and bent molecules. Experimental results show that the solar-to-fuel quantum efficiency is a reciprocal function of the flake size. It also indicates that the consumed electron rate per edge atom is two orders of magnitude larger than the in-plane intrinsic defects. Further, nanoscale redox mapping at the monolayer WSe
2
–liquid interface confirms that the edge is the most preferred region for charge transfer. Our results pave the way for designing a new class of monolayer transition metal dichalcogenides with reconstructed edges as a non-precious co-catalyst for wired or wireless hydrogen evolution or CO
2
reduction reactions.
Abstract
Photocatalytic formation of hydrocarbons using solar energy via artificial photosynthesis is a highly desirable renewable-energy source for replacing conventional fossil fuels. Using an
l
...-cysteine-based hydrothermal process, here we synthesize a carbon-doped SnS
2
(SnS
2
-C) metal dichalcogenide nanostructure, which exhibits a highly active and selective photocatalytic conversion of CO
2
to hydrocarbons under visible-light. The interstitial carbon doping induced microstrain in the SnS
2
lattice, resulting in different photophysical properties as compared with undoped SnS
2
. This SnS
2
-C photocatalyst significantly enhances the CO
2
reduction activity under visible light, attaining a photochemical quantum efficiency of above 0.7%. The SnS
2
-C photocatalyst represents an important contribution towards high quantum efficiency artificial photosynthesis based on gas phase photocatalytic CO
2
reduction under visible light, where the in situ carbon-doped SnS
2
nanostructure improves the stability and the light harvesting and charge separation efficiency, and significantly enhances the photocatalytic activity.
Flexible supercapacitors, a state‐of‐the‐art material, have emerged with the potential to enable major advances in for cutting‐edge electronic applications. Flexible supercapacitors are governed by ...the fundamentals standard for the conventional capacitors but provide high flexibility, high charge storage and low resistance of electro active materials to achieve high capacitance performance. Conducting polymers (CPs) are among the most potential pseudocapacitor materials for the foundation of flexible supercapacitors, motivating the existing energy storage devices toward the future advanced flexible electronic applications due to their high redox active‐specific capacitance and inherent elastic polymeric nature. This review focuses on different types of CPs‐based supercapacitor, the relevant fabrication methods and designing concepts. It describes recent developments and remaining challenges in this field, and its impact on the future direction of flexible supercapacitor materials and relevant device fabrications.
The conducting polymer‐based redox materials are bringing a revolution in the flexible pseudo‐capacitor applications. The future of the CPs‐based flexible energy storage devices hold even greater promise for a novel low cost, light‐weight and highly flexible devices.
The production of renewable solar fuel through CO2 photoreduction, namely artificial photosynthesis, has gained tremendous attention in recent times due to the limited availability of fossil-fuel ...resources and global climate change caused by rising anthropogenic CO2 in the atmosphere. In this study, graphene oxide (GO) decorated with copper nanoparticles (Cu-NPs), hereafter referred to as Cu/GO, has been used to enhance photocatalytic CO2 reduction under visible-light. A rapid one-pot microwave process was used to prepare the Cu/GO hybrids with various Cu contents. The attributes of metallic copper nanoparticles (∼4–5 nm in size) in the GO hybrid are shown to significantly enhance the photocatalytic activity of GO, primarily through the suppression of electron–hole pair recombination, further reduction of GO’s bandgap, and modification of its work function. X-ray photoemission spectroscopy studies indicate a charge transfer from GO to Cu. A strong interaction is observed between the metal content of the Cu/GO hybrids and the rates of formation and selectivity of the products. A factor of greater than 60 times enhancement in CO2 to fuel catalytic efficiency has been demonstrated using Cu/GO-2 (10 wt % Cu) compared with that using pristine GO.
Selective formation of 2,5-dimethylfuran (DMF) by hydrogenolysis of lignocellulosic biomass-derived 5-hydroxymethylfurfural (HMF) is highly desirable for renewable liquid biofuel production. Here we ...have synthesized Cu–Pd bimetallic nanoparticles embedded in carbon matrix (Cu–Pd@C) by simple pyrolysis of Pd-impregnated Cu-based metal–organic frameworks (MOFs) followed by conventional hydrogenation route. It was found that Cu–Pd@C-B (solid–gas-phase hydrogenation route) with Cu–Pd bimetallic alloying exhibited brilliant catalytic performance at 120 °C under 15 bar H2 pressure to produce liquid DMF biofuel with 96.5% yield from HMF as compared with the Cu–Pd@C-A catalyst (liquid phase hydrogenation route), which gave 46.4% yield under the same conditions. X-ray photoelectron spectroscopy (XPS) and X-ray absorption near-edge structure (XANES) studies reveal that Pd in Cu–Pd@C-B catalyst is electronically promoted by Cu with the unique intrinsic synergy of increased Pd–Pd bond distance and decreased Cu–Cu bond length, which eventually modulate the local atomic structural environment and result in enhanced catalytic activity. Moreover, the entrapped bimetallic nanoparticles with carbon shells in Cu–Pd@C-B catalyst further protect the active catalytic site from migration, aggregation, and leaching during hydrogenolysis reaction and improve the stability of the catalyst.
Tuning the electronic band structure of black titania to improve photocatalytic performance through conventional band engineering methods has been challenging because of the defect-induced charge ...carrier and trapping sites. In this study, KSCN-modified hydrogenated nickel nanocluster-modified black TiO2 (SCN–H–Ni–TiO2) exhibits enhanced photocatalytic CO2 reduction due to the interfacial dipole effect. Upon combining the experimental and theoretical simulation approach, the presence of an electrostatic interfacial dipole associated with chemisorption of SCN has dramatic effects on the photocatalyst band structure in SCN–H–Ni–TiO2. An interfacial dipole possesses a more negative zeta potential shift of the isoelectric point from 5.20 to 3.20, which will accelerate the charge carrier separation and electron transfer process. Thiocyanate ion passivation on black TiO2 demonstrated an increased work function around 0.60 eV, which was induced by the interracial dipole effect. Overall, the SCN–H–Ni–TiO2 photocatalyst showed an enhanced CO2 reduction to solar fuel yield by 2.80 times higher than H–Ni–TiO2 and retained around 88% product formation yield after 40 h.
Dual‐Atom Molecular Catalysts
In article number 2103823, Satyanarayana Samireddi, Kuei‐Hsien Chen, Li‐Chyong Chen, and co‐workers present a bimetallic corrole macrocycle‐N4 based dual atom molecular ...catalyst on carbon nanotube support as a promising cost‐effective nonprecious electrocatalyst for oxygen reduction reaction in hydrogen‐based fuel cell application towards clean energy systems with zero carbon emission.
Non‐precious metal catalysts of the oxygen reduction reaction are highly favored for use in polymer electrolyte fuel cells (PEFC) because of their relatively low cost. Here, a new ...carbon‐black‐supported pyrolyzed Co‐corrole (py‐Co‐corrole/C) catalyst of the oxygen reduction reaction (ORR) in a PEFC cathode is demonstrated to have high catalytic performance. The py‐Co‐corrole/C at 700 °C exhibits optimized ORR activity and participates in a direct four‐electron reduction pathway for the reduction of O2 to H2O. The H2‐O2 PEFC test of py‐Co‐corrole/C in the cathode reveals a maximum power density of 275 mW cm−2, which yields a higher performance and a lower Co loading than previous studies of Co‐based catalysts for PEFCs. The enhancement of the ORR activity of py‐Co‐corrole/C is attributable to the four‐coordinated Co‐corrole structure and the oxidation state of the central cobalt.
Pyrolyzed Co‐corrole supported by carbon black catalyzes the oxygen reduction reaction (ORR) by a direct four‐electron reduction pathway for the reduction of O2 to H2O and exhibits high activity as the cathode catalyst of polymer electrolyte fuel cells. The pyrolysis changes the coordination structure and oxidation state of Co‐corrole, leading to the increase in ORR activity.
A bimetallic macrocyclic-N4 complex, FCC, consisting of a Co-corrole core equipped with a peripheral ferrocene has been synthesized. The complex structure was thoroughly characterized using single ...crystal X-ray diffraction. The Co-corrole, mono-substituted with a peripheral Fe-complex, exhibited unique characteristics after its pyrolysis for oxygen reduction reaction (ORR) activity. Carbon black supported FCC, pyrolyzed at 500 degree C, gives an electrocatalyst with a bimetallic (Co and Fe) active center, which facilitates ORR via a 4-electron pathway. The new non-precious bimetallic electrocatalyst exhibits a high electron transfer number of more than 3.95, with a H2O2 yield of below 2.3%, over the potential range of 0.2-0.8 V for ORR in acidic medium, which is superior to pyrolyzed Co-corroles. The enhanced ORR activity for the catalyst derived from this technique provides a new prospect for next-generation non-precious N4 electrocatalysts for fuel cell applications.
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