Sunlight-driven CO2 hydrogenation
has drawn tremendous
attention. However, selective CH4 formation via CO2 photoreduction is very challenging. Herein, we report a metal
oxide semiconductor heterojunction consisting of BiVO4 and
WO3 as a photocatalyst for the efficient conversion of
carbon dioxide (CO2) selectively to methane (105 μmol
g–1 h–1) under visible light in
the absence of a sacrificial agent. Wise selection of the reaction
medium and the strategically tuned heterojunction upon strain relaxation
suppresses the competitive hydrogen generation reaction. The detailed
photophysical, photoelectrochemical, and X-ray absorption spectroscopy
studies pointed to the Z-scheme mechanism of electron transfer, which
favors superior electron and hole separation compared to the individual
components of the composite catalyst and other well-known photocatalysts
reported for CO2 reduction. The observations are further
corroborated by experimental diffuse reflectance infrared Fourier
transform spectroscopy and theoretical density-functional theory calculations,
which reveal that the heterojunction has a lower free-energy barrier
for CO2 conversion to CH4 due to the larger
stabilization of the *CH2O intermediate on the strain-relaxed
heterojunction surface, in comparison to the pristine BiVO4 surface. The present work provides fundamental insights for constructing
high-performance heterojunction photocatalysts for the selective conversion
of CO2 to desired chemicals and fuels.
A facile
non-template-assisted mechanical ball milling technique
was employed to generate a PdBi alloy catalyst. The induced lattice
strain upon the milling time caused a shift of the d-band center,
thereby enhancing the oxygen reduction reaction (ORR) catalytic activity.
Additionally, the Pd–O reduction potential and adsorbed OH
coverage used as descriptors stipulated the cause of the enhanced
ORR activity upon the increased milling interval. Redox properties
of surface Pd are directly correlated with a positive shift in the
Pd–O reduction potential and OH surface coverage. Hence, by
deconvoluting the lattice strain and the role of the descriptor species
we achieved a catalyst system with a specific activity 5.4× higher
than that of commercial Pt/C, as well as an improved durability. The
experimental observation is well-corroborated by a theoretical simulation
done by inducing strain to the system externally.
Direct photocatalytic conversion of CO2 to ethanol remains a scientific challenge because of the sluggish kinetics of C-C coupling and complex multielectron transfer processes. To achieve a green transformation of...
The discovery of new materials for efficient transformation of carbon dioxide (CO 2 ) into desired fuel can revolutionize large-scale renewable energy storage and mitigate environmental damage due to carbon emissions. In this work, we discovered an operando generated stable Ni−In kinetic phase that selectively converts CO 2 to methanol (CTM) at low pressure compared to the state-of-the-art materials. The catalytic nature of a well-known methanation catalyst, nickel, has been tuned with the introduction of inactive indium, which enhances the CTM process. The remarkable change in the mechanistic pathways toward methanol production has been mapped by operando diffuse reflectance infrared Fourier transform spectroscopy analysis, corroborated by first-principles calculations. The ordered arrangement and pronounced electronegativity difference between metals are attributed to the complete shift in mechanism. The approach and findings of this work provide a unique advance toward the next-generation catalyst discovery for going beyond the state-of-the-art in CO 2 reduction technologies.
The development of an efficient photocatalyst for C2 product formation from CO 2 is of urgent importance toward the deployment of solar-fuel production. Here, we report a template-free, cost-effective synthetic strategy to develop a carbazole-derived porous organic polymer (POP)-based composite catalyst. The composite catalyst is comprised of In 2.77 S 4 and porous organic polymer (POP) and is held together by inducedpolarity-driven electrostatic interaction. Utilizing the synergy of the catalytically active In centers and light-harvesting POPs, the catalyst showed 98.9% selectivity toward the generation of C 2 H 4 , with a formation rate of 67.65 μmol g −1 h −1 . Two different oxidation states of the In 2.77 S 4 spinel were exploited for the C−C coupling process, and this was investigated by X-ray photoelectron spectroscopy (XPS), X-ray absorption spectroscopy (XAS), and density functional theory (DFT) calculations. The role of POP was elucidated via several photophysical and photoelectrochemical studies. The electron transfer was mapped by several correlated approaches, which assisted in establishing the Z-scheme mechanism. Furthermore, the mechanism of C 2 H 4 formation was extensively investigated using density functional theory (DFT) calculations from multiple possible pathways.
Rational design of efficient electrode materials for fuel cell, water oxidation, and the metal-air battery is now cutting–edge activity in renewable energy research. In this regard, tuning the activity at...
Fast photogenerated charge recombination and inappropriate bandgap for visible light driven charge generation hinders the performance of TiO2. In this study, TiO2 was activated for visible light driven CO2 reduction...
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