Single‐atom‐layer catalysts with fully activated basal‐atoms will provide a solution to the low loading‐density bottleneck of single‐atom catalysts. Herein, we activate the majority of the basal ...sites of monolayer MoS2, by doping Co ions to induce long‐range ferromagnetic order. This strategy, as revealed by in situ synchrotron radiation microscopic infrared spectroscopy and electrochemical measurements, could activate more than 50 % of the originally inert basal‐plane S atoms in the ferromagnetic monolayer for the hydrogen evolution reaction (HER). Consequently, on a single monolayer of ferromagnetic MoS2 measured by on‐chip micro‐cell, a current density of 10 mA cm−2 could be achieved at the overpotential of 137 mV, corresponding to a mass activity of 28, 571 Ag−1, which is two orders of magnitude higher than the multilayer counterpart. Its exchange current density of 75 μA cm−2 also surpasses most other MoS2‐based catalysts. Experimental results and theoretical calculations show the activation of basal plane S atoms arises from an increase of electronic density around the Fermi level, promoting the H adsorption ability of basal‐plane S atoms.
A possible way to trigger hydrogen evolution reaction (HER) activity of the basal‐plane sites and make a MoS2 monolayer a single‐atom‐layer catalyst, is through long‐range ferromagnetism order induced by magnetic cobalt ion doping. The effect of the doping promotes the hydrogen adsorption ability of basal S sites.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
The chlor-alkali process plays an essential and irreplaceable role in the modern chemical industry due to the wide-ranging applications of chlorine gas. However, the large overpotential and low ...selectivity of current chlorine evolution reaction (CER) electrocatalysts result in significant energy consumption during chlorine production. Herein, we report a highly active oxygen-coordinated ruthenium single-atom catalyst for the electrosynthesis of chlorine in seawater-like solutions. As a result, the as-prepared single-atom catalyst with Ru-O
moiety (Ru-O
SAM) exhibits an overpotential of only ~30 mV to achieve a current density of 10 mA cm
in an acidic medium (pH = 1) containing 1 M NaCl. Impressively, the flow cell equipped with Ru-O
SAM electrode displays excellent stability and Cl
selectivity over 1000 h continuous electrocatalysis at a high current density of 1000 mA cm
. Operando characterizations and computational analysis reveal that compared with the benchmark RuO
electrode, chloride ions preferentially adsorb directly onto the surface of Ru atoms on Ru-O
SAM, thereby leading to a reduction in Gibbs free-energy barrier and an improvement in Cl
selectivity during CER. This finding not only offers fundamental insights into the mechanisms of electrocatalysis but also provides a promising avenue for the electrochemical synthesis of chlorine from seawater electrocatalysis.
Abstract
As diversified reaction paths exist over practical catalysts towards CO
2
hydrogenation, it is highly desiderated to precisely control the reaction path for developing efficient catalysts. ...Herein, we report that the ensemble of Pt single atoms coordinated with oxygen atoms in MIL-101 (Pt
1
@MIL) induces distinct reaction path to improve selective hydrogenation of CO
2
into methanol. Pt
1
@MIL achieves the turnover frequency number of 117 h
−1
in DMF under 32 bar at 150 °C, which is 5.6 times that of Pt
n
@MIL. Moreover, the selectivity for methanol is 90.3% over Pt
1
@MIL, much higher than that (13.3%) over Pt
n
@MIL with CO as the major product. According to mechanistic studies, CO
2
is hydrogenated into HCOO* as the intermediate for Pt
1
@MIL, whereas COOH* serves as the intermediate for Pt
n
@MIL. The unique reaction path over Pt
1
@MIL not only lowers the activation energy for the enhanced catalytic activity, but also contributes to the high selectivity for methanol.
Perovskite solar cells (Pero-SCs) exhibited a bright future for the next generation of photovoltaic technology because of their high power conversion efficiency (PCE), low cost, and simple solution ...process. The certified laboratory-scale PCE has reached 25.7% referred to small scale (2) of Pero-SCs. However, with the increase of the area to module scale, the PCE drops dramatically mainly due to the inadequate regulation of growing large-area perovskite films. Therefore, there is a dire need to produce high-quality perovskite films for large-area photovoltaic modules. Herein, we summarize the recent advances in perovskite photovoltaic modules (PPMs) with particular attention paid to the coating methods, as well as the growth regulation of the high-quality and large-area perovskite films. Furthermore, this study encompasses future development directions and prospects for PPMs.
In many organic reactions, the O2 activation process involves a key step where inert ground triplet O2 is excited to produce highly reactive singlet O2. It remains elusive what factor induces the ...change in the electron spin state of O2 molecules, although it has been discovered that the presence of noble metal nanoparticles can promote the generation of singlet O2. In this work, we first demonstrate that surface facet is a key parameter to modulate the O2 activation process on metal nanocrystals, by employing single-facet Pd nanocrystals as a model system. The experimental measurements clearly show that singlet O2 is preferentially formed on {100} facets. The simulations further elucidate that the chemisorption of O2 to the {100} facets can induce a spin–flip process in the O2 molecules, which is achieved via electron transfer from Pd surface to O2. With the capability of tuning O2 activation, we have been able to further implement the {100}-faceted nanocubes in glucose oxidation. It is anticipated that this study will open a door to designing noble metal nanocatalysts for O2 activation and organic oxidation. Another perspective of this work would be the controllability in tailoring the cancer treatment materials for high 1O2 production efficiency, based on the facet control of metal nanocrystals. In the cases of both organic oxidation and cancer treatment, it has been exclusively proven that the efficiency of producing singlet O2 holds the key to the performance of Pd nanocrystals in the applications.
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Perovskite electrocatalysts strongly rely on electronic structure regulation, especially for electron configuration (eg) and conductivity. However, current regulation strategies inevitably involve ...ambiguous entanglement of crystals, electrons, and spin degrees of freedom. Here, we developed a spin-state regulation method to optimize oxygen evolution reaction (OER) activity by lattice orientation control of LaCoO3 epitaxial films. The different lattice-oriented LaCoO3 films bring different degrees of distortion of the CoO6 octahedron, successfully inducing a spin-state transition of cobalt from a low spin state (LS t2g6eg0) to an intermediate spin state (IS t2g5eg1). X-ray absorption spectroscopy of Co L-edge and O K-edge provides experimental support of spin-state transition in different lattice-oriented LaCoO3 films. As expected, LaCoO3 (100) film possesses optimal eg electron filling, lower adsorption free energy, and higher conductivity, exhibiting better OER performance than the other two films. Our findings demonstrate that electronic state regulation will be a new avenue for the rational design of high-activity perovskite electrocatalysts.
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•A conceptually unique regulation method for perovskite electrocatalysts is described•Synergistic effect contributes to the optimal OER activity•Pure spin-state regulation inspires design of high-activity OER catalysts
Electrochemical water splitting plays a key role to meet the growing energy and environmental crises derived from the excessive utilization of fossil fuels. As one of the half reactions, the oxygen evolution reaction (OER) is important in various renewable oxygen-based electrochemical technologies. Perovskites, as prototype efficient OER catalysts, have attracted extensive interest arising from synergic advantages of their structural stability, rich active sites, and wide-range of controllable electronic states. However, the development of perovskite electrocatalysts has been greatly hampered by optimization of eg electrons and electronic conductivity. To enhance the electrocatalytic activity of perovskite, we demonstrated a spin-state regulation method by lattice orientation control of LaCoO3 epitaxial films to obtain superior OER performance. Moreover, this method of electronic state regulation could provide a guide for the rational design of high-activity perovskite electrocatalysts.
A unique spin-state regulation method has been proposed to optimize oxygen evolution reaction (OER) activity by lattice-oriented control of LaCoO3 epitaxial films. As expected, LaCoO3 (100) film exhibits a better OER catalytic performance than that of LCO (110) and LCO (111) films, making it superior to most reported perovskite electrocatalysts.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Metal–support interactions are of significance in clarifying the support–activity relationship over deposited metal catalysts yet rarely considered on single-atomic-site species. Herein, using two ...single-atomic-site Ir samples supported by the defective metastable phase of titanium dioxide or mesoporous graphitic carbon nitride as the research objects, we demonstrate the effects of metal–support interactions on regulating the geometric and electronic structures of the central Ir species, through which, the catalytic properties are further affected. Experimental results show that the single-atomic-site Ir catalyst supported by the defective metastable phase of titanium dioxide exhibits excellent catalytic performance for the hydrogenation of furfural to furfuryl alcohol, showing outstanding conversion (99%), high selectivity (99%), and good stability that are superior to the mesoporous graphitic carbon nitride supported single-atomic-site Ir sample as well as Ir nanoparticles. First-principles simulations reveal that the excellent catalytic performance of the single-atomic-site Ir on the defective metastable phase of titanium dioxide can be attributed to the appropriate strength of interactions between the active metal sites and the reactant molecules owing to the regulation of the supports.
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It is very important to explore novel synthesis strategies for constructing highly active and inexpensive electrocatalysts for water-splitting. In present work, a novel and efficient ...coordination-polymerization-pyrolysis (CPP) strategy was developed to prepare cobalt phosphide nanoparticles modified N-doped porous carbon spheres (CoP@NPCSs) hybrids as a powerful catalyst for overall water-splitting (OWS). It can be found that both the carbonization temperatures and the metal contents affect the electrocatalytic performances. As a result, a device assembled with CoP@NPCSs demonstrates low potential (1.643 V @ 10 mA·cm–2) and good stabilization for OWS. Besides, other transition metal phosphides (TMPs)-based materials also can be synthesized by the CPP approach, evidencing the generality of the CPP strategy. Here, we not only constructs a high-efficiency OWS catalyst, but also broadens the synthetic methodology of TMPs from nanoscale.
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The indirect dry cooling system, consisting mainly of the dry cooling tower and condenser, keeps energy balance under stable state. However dry cooling tower is easily influenced by the variation of ...ambient condition, like ambient temperature and crosswind, and theses unfavorable effects will affect the operation of the condenser directly and further impact unit efficiency. Therefore it is necessary to study the effects of ambient temperature and crosswind on thermo-flow performance of the tower under energy balance of the indirect dry cooling system. Taking a 600 MW indirect dry cooling system as an example, numerical simulation model of the dry cooling tower and thermal calculation model of the condenser are established respectively. With the method coupling the two models, the pressure, temperature fields and streamlines are presented. The indirect dry cooling system regains equilibrium after ambient condition varies, and parameters of the system under this stable state are obtained. These parameters reflect the effects of ambient conditions on the thermo-flow performance of the tower under energy balance of the system rather than under the condition that the tower is viewed as isolated. When the power unit is steady running with a certain load, outlet water temperature of the tower is approximately linear with ambient temperature, whereas nonlinear with crosswind speed. In addition, the computational models and coupled method mentioned in this paper are proved reliable enough for the performance prediction of the tower under energy balance of the indirect dry cooling system, which is beneficial to the economic and safe operation of the unit.
•Simulation model coupling the dry cooling tower and condenser is established.•The coupled method is based on energy balance of the indirect dry cooling system.•Outlet water temperature of the tower is nonlinear with crosswind speed.•Outlet water temperature of the tower is nearly linear with ambient temperature.•The coupled method is reliable for predictions under various working conditions.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
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