Subnanometric metal clusters usually have unique electronic structures and may display electrocatalytic performance distinctive from single atoms (SAs) and larger nanoparticles (NPs). However, the electrocatalytic performance of clusters, especially the size-activity relationship at the sub-nanoscale, is largely unexplored. Here, we synthesize a series of Ru nanocrystals from single atoms, subnanometric clusters to larger nanoparticles, aiming at investigating the size-dependent activity of hydrogen evolution in alkaline media. It is found that the d band center of Ru downshifts in a nearly linear relationship with the increase of diameter, and the subnanometric Ru clusters with d band center closer to Femi level display a stronger water dissociation ability and thus superior hydrogen evolution activity than SAs and larger nanoparticles. Benefiting from the high metal utilization and strong water dissociation ability, the Ru clusters manifest an ultrahigh turnover frequency of 43.3 s−1 at the overpotential of 100 mV, 36.1-fold larger than the commercial Pt/C.
The electrochemical nitrate (NO3-) reduction reaction (NO3-RR), with much rapider kinetics than the nitrogen (N2) reduction, provides new opportunities to harvest ammonia (NH3) under ambient conditions. However, the NH3 production...
Previous density-functional theory (DFT) calculations show that sub-nanometric Cu clusters (i.e., 13 atoms) favorably generate CH 4 from the CO 2 reduction reaction (CO 2 RR), but experimental evidence is lacking. Herein, a facile impregnation-calcination route towards Cu clusters, having a diameter of about 1.0 nm with about 10 atoms, was developed by double confinement of carbon defects and micropores. These Cu clusters enable high selectivity for the CO 2 RR with a maximum Faraday efficiency of 81.7 % for CH 4. Calculations and experimental results show that the Cu clusters enhance the adsorption of *H and *CO intermediates, thus promoting generation of CH 4 rather than H 2 and CO. The strong interactions between the Cu clusters and defective carbon optimize the electronic structure of the Cu clusters for selectivity and stability towards generation of CH 4. Provided here is the first experimental evidence that sub-nanometric Cu clusters facilitate the production of CH 4 from the CO 2 RR.
Developing low-cost and highly-efficient non-precious metal bifunctional electrocatalysts towards the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is an attractively alternative strategy to solve the environmental pollution problems and energy demands. In this study, metal-organic framework (MOF) derived porous cobalt poly-phosphide (CoP) concave polyhedrons are prepared and explored as superior bifunctional electrocatalysts for the HER and OER. The prepared MOF derived CoP concave polyhedrons show excellent electrocatalytic activity and stability towards the HER and OER in both acidic and alkaline media, with the Tafel slopes of 53 mV dec and 76 mV dec and a current density of 10 mA cm at the overpotentials of -78 and 343 mV for the HER and OER, respectively, which are remarkably superior to those of the transition metal phosphides (TMPs) and comparable to those of the commercial precious metal catalysts. In addition, they also offer efficient catalytic activities and durabilities under neutral and basic conditions for the HER. The results of our study may shed light on the direction towards highly efficient bifunctional TMP electrocatalysts with high phosphorous component.
Fabricating heterostructures
to promote the charge separation and
doping heteroatom to modulate the band gap of the photocatalysts have
been regarded as effective strategies to improve the photocatalytic
performance. However, it is still an unresolved issue of doping element
and fabricating heterostructures with good contact at the same time.
In this study, P nanostructures/P doped graphitic carbon nitride composites
(P@P-g-C3N4) were successfully
composited by a solid reaction route. Various structural characterizations,
including X-ray adsorption near edge structure, indicate that P has
been doped into g-C3N4 and P nanostructures
were directly grown on g-C3N4 to form heterostructures.
As expected, the intimate contacted heterostructured composites exhibit
much enhanced light absorption and high-efficiency transfer and separation
of photogenerated electron–hole pairs, and consequently, the
composites also possess the superior photocatalytic performance in
the rapidly degrading RhB and an efficient H2 production
rate of 941.80 μmolh–1g–1. Systematical studies combining experimental measurements with theoretical
calculations were carried out to expound the underlying reasons behind
the distinct performance. This study pave a one-step way to synthesize
earth abundant element C, N, and P as novel photocatalysts for photochemical
applications.
Electrochemical reduction of CO2 may provide a promising method to mitigate the concentration of CO2 in the atmosphere, and simultaneously convert this greenhouse gas into value‐added fuels or chemicals. However, electrocatalysts for CO2 reduction are mostly powder based; therefore, polymer binders are always employed to make these catalysts useful as working electrodes. As a consequence, plenty of active sites are embedded inside without catalytic performance, causing a relatively low efficiency. On the contrary, self‐supported electrocatalysts do not involve the typical powdering and drop‐coating procedure with the aid of polymer binders or additives, avoiding the weak contact between active materials and current collector. Moreover, the superior self‐supported structure can also provide an accelerated electron transfer, guarantee ample electrolyte access to the active sites, offer large electrochemical surface areas, and increase CO2 adsorption capacity around the active sites, finally leading to the excellent efficiency and long‐term stability in CO2 reduction. In this manuscript, recent advances regarding CO2 reduction by self‐supported electrocatalysts are comprehensively reviewed, including the synthesis methods, chemical compositions, nanostructures, and catalytic efficiencies. Furthermore, the existing challenges and perspectives on the research and development of self‐supported electrocatalysts for CO2 reduction are discussed.
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