Production of methanol from electrochemical reduction of carbon dioxide is very attractive. However, achieving high Faradaic efficiency with high current density using facile prepared catalysts ...remains to be a challenge. Herein we report that copper selenide nanocatalysts have outstanding performance for electrochemical reduction of carbon dioxide to methanol, and the current density can be as high as 41.5 mA cm
with a Faradaic efficiency of 77.6% at a low overpotential of 285 mV. The copper and selenium in the catalysts cooperate very well for the formation of methanol. The current density is higher than those reported up to date with very high Faradaic efficiency for producing methanol. As far as we know, this is the first work for electrochemical reduction of carbon dioxide using copper selenide as the catalyst.
Selective reduction of ketone/aldehydes to alcohols is of great importance in green chemistry and chemical engineering. Highly efficient catalysts are still demanded to work under mild conditions, ...especially at room temperature. Here we present a synergistic function of single-atom palladium (Pd
) and nanoparticles (Pd
) on TiO
for highly efficient ketone/aldehydes hydrogenation to alcohols at room temperature. Compared to simple but inferior Pd
/TiO
and Pd
/TiO
catalysts, more than twice activity enhancement is achieved with the Pd
/TiO
catalyst that integrates both Pd
and Pd NPs on mesoporous TiO
supports, obtained by a simple but large-scaled spray pyrolysis route. The synergistic function of Pd
and Pd
is assigned so that the partial Pd
dispersion contributes enough sites for the activation of C=O group while Pd
site boosts the dissociation of H
molecules to H atoms. This work not only contributes a superior catalyst for ketone/aldehydes hydrogenation, but also deepens the knowledge on their hydrogenation mechanism and guides people to engineer the catalytic behaviors as needed.
The electrochemical reduction of CO2 could play an important role in addressing climate-change issues and global energy demands as part of a carbon-neutral energy cycle. Single-atom catalysts can ...display outstanding electrocatalytic performance; however, given their single-site nature they are usually only amenable to reactions that involve single molecules. For processes that involve multiple molecules, improved catalytic properties could be achieved through the development of atomically dispersed catalysts with higher complexities. Here we report a catalyst that features two adjacent copper atoms, which we call an ‘atom-pair catalyst’, that work together to carry out the critical bimolecular step in CO2 reduction. The atom-pair catalyst features stable Cu10–Cu1x+ pair structures, with Cu1x+ adsorbing H2O and the neighbouring Cu10 adsorbing CO2, which thereby promotes CO2 activation. This results in a Faradaic efficiency for CO generation above 92%, with the competing hydrogen evolution reaction almost completely suppressed. Experimental characterization and density functional theory revealed that the adsorption configuration reduces the activation energy, which generates high selectivity, activity and stability under relatively low potentials.Anchored single-atom catalysts have recently been shown to be very active for various processes, however, a catalyst that features two adjacent copper atoms—which we call an atom-pair catalyst—is now reported. The Cu10–Cu1x+ pair structures work together to carry out the critical bimolecular step in CO2 reduction.
Abstract
Effecting the synergistic function of single metal atom sites and their supports is of great importance to achieve high-performance catalysts. Herein, we successfully fabricate ...polyoxometalates (POMs)-stabilized atomically dispersed platinum sites by employing three-dimensional metal-organic frameworks (MOFs) as the finite spatial skeleton to govern the accessible quantity, spatial dispersion, and mobility of metal precursors around each POM unit. The isolated single platinum atoms (Pt
1
) are steadily anchored in the square-planar sites on the surface of monodispersed Keggin-type phosphomolybdic acid (PMo) in the cavities of various MOFs, including MIL-101, HKUST-1, and ZIF-67. In contrast, either the absence of POMs or MOFs yielded only platinum nanoparticles. Pt
1
-PMo@MIL-101 are seven times more active than the corresponding nanoparticles in the diboration of phenylacetylene, which can be attributed to the synergistic effect of the preconcentration of organic reaction substrates by porous MOFs skeleton and the decreased desorption energy of products on isolated Pt atom sites.
The construction of highly active and stable non-noble-metal electrocatalysts for hydrogen and oxygen evolution reactions is a major challenge for overall water splitting. Herein, we report a novel ...hybrid nanostructure with CoP nanoparticles (NPs) embedded in a N-doped carbon nanotube hollow polyhedron (NCNHP) through a pyrolysis–oxidation–phosphidation strategy derived from core–shell ZIF-8@ZIF-67. Benefiting from the synergistic effects between highly active CoP NPs and NCNHP, the CoP/NCNHP hybrid exhibited outstanding bifunctional electrocatalytic performances. When the CoP/NCNHP was employed as both the anode and cathode for overall water splitting, a potential as low as 1.64 V was needed to achieve the current density of 10 mA·cm–2, and it still exhibited superior activity after continuously working for 36 h with nearly negligible decay in potential. Density functional theory calculations indicated that the electron transfer from NCNHP to CoP could increase the electronic states of the Co d-orbital around the Fermi level, which could increase the binding strength with H and therefore improve the electrocatalytic performance. The strong stability is attributed to high oxidation resistance of the CoP surface protected by the NCNHP.
Abstract
Atomically dispersed metal-N-C structures are efficient active sites for catalyzing benzene oxidation reaction (BOR). However, the roles of N and C atoms are still unclear. We report a ...polymerization-regulated pyrolysis strategy for synthesizing single-atom Fe-based catalysts, and present a systematic study on the coordination effect of Fe-N
x
C
y
catalytic sites in BOR. The special coordination environment of single-atom Fe sites brings a surprising discovery: Fe atoms anchored by four-coordinating N atoms exhibit the highest BOR performance with benzene conversion of 78.4% and phenol selectivity of 100%. Upon replacing coordinated N atoms by one or two C atoms, the BOR activities decrease gradually. Theoretical calculations demonstrate the coordination pattern influences not only the structure and electronic features, but also the catalytic reaction pathway and the formation of key oxidative species. The increase of Fe-N coordination number facilitates the generation and activation of the crucial intermediate O=Fe=O species, thereby enhancing the BOR activity.
A central topic in single-atom catalysis is building strong interactions between single atoms and the support for stabilization. Herein we report the preparation of stabilized single-atom catalysts ...via a simultaneous self-reduction stabilization process at room temperature using ultrathin two-dimensional Ti3–x C2T y MXene nanosheets characterized by abundant Ti-deficit vacancy defects and a high reducing capability. The single atoms therein form strong metal–carbon bonds with the Ti3–x C2T y support and are therefore stabilized onto the sites previously occupied by Ti. Pt-based single-atom catalyst (SAC) Pt1/Ti3–x C2T y offers a green route to utilizing greenhouse gas CO2, via the formylation of amines, as a C1 source in organic synthesis. DFT calculations reveal that, compared to Pt nanoparticles, the single Pt atoms on Ti3–x C2T y support feature partial positive charges and atomic dispersion, which helps to significantly decrease the adsorption energy and activation energy of silane, CO2, and aniline, thereby boosting catalytic performance. We believe that these results would open up new opportunities for the fabrication of SACs and the applications of MXenes in organic synthesis.
The practical application of hydrogen evolution reaction (HER) through water splitting depends on the development of low cost and efficient non-noble-metal catalysts. As a potential electrocatalyst, ...the improvement of HER performance catalyzed by nanostructured transition metal phosphides still remains a great challenge. Tuning the novel nanostructure, morphology, and electronic state from nanoscale is of great important to achieve highly efficient HER electrocatalysts. Herein, we first developed an electronic structure and d-band center control engineering for accelerating the HER process in both acid and alkaline media over M-doped CoP (M = Ni, Mn, Fe) hollow polyhedron frames (HPFs), which were synthesized by a self-templating transformation (STT) strategy. Impressively, the HER electrocatalytic activity can be maximumly promoted and maintained at least 21 h for Ni-CoP/HPFs catalyst. Synchrotron-based X-ray absorption near-edge structure, X-ray photoelectron spectroscopy, auger electron spectroscopy, ultraviolet photoemission spectroscopy and density functional theory calculations consistently reveal the improved performance is attributed to the changes of the electronic structure and the downshift of d-band center after metal doping. The Ni-CoP/HPFs catalyst also indicates excellent activity with a cell voltage of 1.43 V to achieve the current density of 10 mA cm−2 and superior stability when it was employed as a cathode for HER and an anode for urea oxidation in 1 M KOH with 0.5 M urea. The success modulation of HER performance in current STT strategy will provide a promising pathway for designing various transition metal-doped compounds for energy-related catalysis processes.
An electronic structure and d-band center control engineering was developed for accelerating the HER process over M-doped CoP (M = Ni, Mn, Fe) hollow polyhedron frames (HPFs) from a self-templating transformation strategy in atomic scale. The optimized Ni-CoP/HPFs catalyst can be used as a bifunctional catalyst for energy-efficient electrocatalytic hydrogen production due to the high urea oxidation performance. Display omitted
•An electronic structure and d-band center control engineering for accelerating the HER process was developed.•The M-doped CoP hollow polyhedron frames were synthesized by a self-templating transformation strategy.•The HER activity can be maximumly promoted and maintained for Ni-CoP/HPFs catalyst.•The Ni-CoP/HPFs can be used as a bifunctional catalyst for energy-efficient hydrogen production.•Reasonable mechanism for the improved catalytic activity was proposed.
For electrocatalysts for the hydrogen evolution reaction (HER), encapsulating transition metal phosphides (TMPs) into nitrogen‐doped carbon materials has been known as an effective strategy to ...elevate the activity and stability. Yet still, it remains unclear how the TMPs work synergistically with the N‐doped support, and which N configuration (pyridinic N, pyrrolic N, or graphitic N) contributes predominantly to the synergy. Here we present a HER electrocatalyst (denoted as MoP@NCHSs) comprising MoP nanoparticles encapsulated in N‐doped carbon hollow spheres, which displays excellent activity and stability for HER in alkaline media. Results of experimental investigations and theoretical calculations indicate that the synergy between MoP and the pyridinic N can most effectively promote the HER in alkaline media.
The effect of the dopant: In the electrocatalyst comprising MoP nanoparticles encapsulated by nitrogen‐doped carbon, the sites where MoP interacts with pyridinic N (but not pyrrolic N or graphitic N) lead to increased electron density on the nitrogen‐doped carbon, as well as optimized adsorption of H* and OH*, all of which help to accelerate the hydrogen evolution reaction in alkaline media.
High-efficiency water electrolysis is the key to sustainable energy. Here we report a highly active and durable RuIrO
(x ≥ 0) nano-netcage catalyst formed during electrochemical testing by in-situ ...etching to remove amphoteric ZnO from RuIrZnO
hollow nanobox. The dispersing-etching-holing strategy endowed the porous nano-netcage with a high exposure of active sites as well as a three-dimensional accessibility for substrate molecules, thereby drastically boosting the electrochemical surface area (ECSA). The nano-netcage catalyst achieved not only ultralow overpotentials at 10 mA cm
for hydrogen evolution reaction (HER; 12 mV, pH = 0; 13 mV, pH = 14), but also high-performance overall water electrolysis over a broad pH range (0 ~ 14), with a potential of mere 1.45 V (pH = 0) or 1.47 V (pH = 14) at 10 mA cm
. With this universal applicability of our electrocatalyst, a variety of readily available electrolytes (even including waste water and sea water) could potentially be directly used for hydrogen production.
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