Facet-switching of rate-determining step on copper in CO2-to-ethylene electroreduction.

Reduction of carbon dioxide (CO2) by renewable electricity to produce multicarbon chemicals, such as ethylene (C2H4), continues to be a challenge because of insufficient Faradaic efficiency, low production rates, and complex mechanistic pathways. Here, we report that the rate-determining steps (RDS) on common copper (Cu) surfaces diverge in CO2 electroreduction, leading to distinct catalytic performances. Through a combination of experimental and computational studies, we reveal that C─C bond-making is the RDS on Cu(100), whereas the protonation of *CO with adsorbed water becomes rate-limiting on Cu(111) with a higher energy barrier. On an oxide-derived Cu(100)-dominant Cu catalyst, we reach a high C2H4 Faradaic efficiency of 72%, partial current density of 359 mA cm-2, and long-term stability exceeding 100 h at 500 mA cm-2, greatly outperforming its Cu(111)-rich counterpart. We further demonstrate constant C2H4 selectivity of >60% over 70 h in a membrane electrode assembly electrolyzer with a full-cell energy efficiency of 23.4%.

Efficient and stable acidic CO2 electrolysis to formic acid by a reservoir structure design.

Electrochemical synthesis of valuable chemicals and feedstocks through carbon dioxide (CO2) reduction in acidic electrolytes can surmount the considerable CO2 loss in alkaline and neutral conditions. However, achieving high productivity, while operating steadily in acidic electrolytes, remains a big challenge owing to the severe competing hydrogen evolution reaction. Here, we show that vertically grown bismuth nanosheets on a gas-diffusion layer can create numerous cavities as electrolyte reservoirs, which confine in situ-generated hydroxide and potassium ions and limit inward proton diffusion, producing locally alkaline environments. Based on this design, we achieve formic acid Faradaic efficiency of 96.3% and partial current density of 471 mA cm-2 at pH 2. When operated in a slim continuous-flow electrolyzer, the system exhibits a full-cell formic acid energy efficiency of 40% and a single pass carbon efficiency of 79% and performs steadily over 50 h. We further demonstrate the production of pure formic acid aqueous solution with a concentration of 4.2 weight %.

Gerhardtite as a Precursor to an Efficient CO-to-Acetate Electroreduction Catalyst.

Carbon-carbon coupling electrochemistry on a conventional copper (Cu) catalyst still undergoes low selectivity among many different multicarbon (C2+) chemicals, posing a grand challenge to achieve a single C2+ product. Here, we demonstrate a laser irradiation synthesis of a gerhardtite mineral, Cu2(OH)3NO3, as a catalyst precursor to make a Cu catalyst with abundant stacking faults under reducing conditions. Such structural perturbation modulates electronic microenvironments of Cu, leading to improved d-electron back-donation to the antibonding orbital of *CO intermediates and thus strengthening *CO adsorption. With increased *CO coverage on the defect-rich Cu, we report an acetate selectivity of 56 ± 2% (compared to 31 ± 1% for conventional Cu) and a partial current density of 222 ± 7 mA per square centimeter in CO electroreduction. When run at 400 mA per square centimeter for 40 h in a flow reactor, this catalyst produces 68.3 mmol of acetate throughout. This work highlights the value of a Cu-containing mineral phase in accessing suitable structures for improved selectivity to a single desired C2+ product.

Efficient acidic hydrogen evolution in proton exchange membrane electrolyzers over a sulfur-doped marcasite-type electrocatalyst.

Large-scale deployment of proton exchange membrane (PEM) water electrolyzers has to overcome a cost barrier resulting from the exclusive adoption of platinum group metal (PGM) catalysts. Ideally, carbon-supported platinum used at cathode should be replaced with PGM-free catalysts, but they often undergo insufficient activity and stability subjecting to corrosive acidic conditions. Inspired by marcasite existed under acidic environments in nature, we report a sulfur doping-driven structural transformation from pyrite-type cobalt diselenide to pure marcasite counterpart. The resultant catalyst drives hydrogen evolution reaction with low overpotential of 67 millivolts at 10 milliamperes per square centimeter and exhibits no degradation after 1000 hours of testing in acid. Moreover, a PEM electrolyzer with this catalyst as cathode runs stably over 410 hours at 1 ampere per square centimeter and 60°C. The marked properties arise from sulfur doping that not only triggers formation of acid-resistant marcasite structure but also tailors electronic states (e.g., work function) for improved hydrogen diffusion and electrocatalysis.

3D Printing Flexible Sodium-Ion Microbatteries with Ultrahigh Areal Capacity and Robust Rate Capability.

Rechargeable sodium-ion microbatteries (NIMBs) constructed using low-cost and abundant raw materials in planar configuration with both cathode and anode on the same substrate hold promise for powering coplanar microelectronics, but are hindered by the low areal capacity owing to the thin microelectrodes. Here, a prototype of planar and flexible 3D-printed NIMBs is demonstrated with 3D interconnected conductive thick microelectrodes for ultrahigh areal capacity and boosted rate capability. Rationally optimized 3D printable inks with appropriate viscosities and high conductivity allow the multilayer printing of NIMB microelectrodes reaching a very high thickness of ≈1200 µm while maintaining effective ion and electron-transfer pathways in them. Consequently, the 3D-printed NIMBs deliver superior areal capacity of 4.5 mAh cm-2 (2 mA cm-2 ), outperforming the state-of-the-art printed microbatteries. The NIMBs show enhanced rate capability with 3.6 mAh cm-2 at 40 mA cm-2 and robust long-term cycle life up to 6000 cycles. Furthermore, the planar NIMB microelectrodes, despite the large thickness, exhibit decent mechanical flexibility under various bending conditions. This work opens a new avenue for the construction of high-performance NIMBs with thick microelectrodes capable of powering flexible microelectronics.

Identification of Cu(100)/Cu(111) Interfaces as Superior Active Sites for CO Dimerization During CO2 Electroreduction.

The electrosynthesis of valuable multicarbon chemicals using carbon dioxide (CO2) as a feedstock has substantially progressed recently but still faces considerable challenges. A major difficulty lines in the sluggish kinetics of forming carbon-carbon (C-C) bonds, especially in neutral media. We report here that oxide-derived copper crystals enclosed by six {100} and eight {111} facets can reduce CO2 to multicarbon products with a high Faradaic efficiency of 74.9 ± 1.7% at a commercially relevant current density of 300 mA cm-2 in 1 M KHCO3 (pH ∼ 8.4). By combining the experimental and computational studies, we uncovered that Cu(100)/Cu(111) interfaces offer a favorable local electronic structure that enhances *CO adsorption and lowers C-C coupling activation energy barriers, performing superior to Cu(100) and Cu(111) surfaces, respectively. On this catalyst, no obvious degradation was observed at 300 mA cm-2 over 50 h of continuous operation.

Stabilizing indium sulfide for CO2 electroreduction to formate at high rate by zinc incorporation.

Recently developed solid-state catalysts can mediate carbon dioxide (CO2) electroreduction to valuable products at high rates and selectivities. However, under commercially relevant current densities of > 200 milliamperes per square centimeter (mA cm-2), catalysts often undergo particle agglomeration, active-phase change, and/or element dissolution, making the long-term operational stability a considerable challenge. Here we report an indium sulfide catalyst that is stabilized by adding zinc in the structure and shows dramatically improved stability. The obtained ZnIn2S4 catalyst can reduce CO2 to formate with 99.3% Faradaic efficiency at 300 mA cm-2 over 60 h of continuous operation without decay. By contrast, similarly synthesized indium sulfide without zinc participation deteriorates quickly under the same conditions. Combining experimental and theoretical studies, we unveil that the introduction of zinc largely enhances the covalency of In-S bonds, which "locks" sulfur-a catalytic site that can activate H2O to react with CO2, yielding HCOO* intermediates-from being dissolved during high-rate electrolysis.

Hierarchical Copper with Inherent Hydrophobicity Mitigates Electrode Flooding for High-Rate CO2 Electroreduction to Multicarbon Products.

Copper is currently the material with the most promise as catalyst to drive carbon dioxide (CO2) electroreduction to produce value-added multicarbon (C2+) compounds. However, a copper catalyst on a carbon-based gas diffusion layer electrode often has poor stability-especially when performing at high current densities-owing to electrolyte flooding caused by the hydrophobicity decrease of the gas diffusion layer during operation. Here, we report a bioinspired copper catalyst on a gas diffusion layer that mimics the unique hierarchical structuring of Setaria's hydrophobic leaves. This hierarchical copper structure endows the CO2 reduction electrode with sufficient hydrophobicity to build a robust gas-liquid-solid triple-phase boundary, which can not only trap more CO2 close to the active copper surface but also effectively resist electrolyte flooding even under high-rate operation. We consequently achieved a high C2+ production rate of 255 ± 5.7 mA cm-2 with a 64 ± 1.4% faradaic efficiency, as well as outstanding operational stability at 300 mA cm-2 over 45 h in a flow reactor, largely outperforming its wettable copper counterparts.

An Efficient Turing-Type Ag2 Se-CoSe2 Multi-Interfacial Oxygen-Evolving Electrocatalyst*.

Although the Turing structures, or stationary reaction-diffusion patterns, have received increasing attention in biology and chemistry, making such unusual patterns on inorganic solids is fundamentally challenging. We report a simple cation exchange approach to produce Turing-type Ag2 Se on CoSe2 nanobelts relied on diffusion-driven instability. The resultant Turing-type Ag2 Se-CoSe2 material is highly effective to catalyze the oxygen evolution reaction (OER) in alkaline electrolytes with an 84.5 % anodic energy efficiency. Electrochemical measurements show that the intrinsic OER activity correlates linearly with the length of Ag2 Se-CoSe2 interfaces, determining that such Turing-type interfaces are more active sites for OER. Combing X-ray absorption and computational simulations, we ascribe the excellent OER performance to the optimized adsorption energies for critical oxygen-containing intermediates at the unconventional interfaces.

Degradation of benzotriazole by sulfate radical-based advanced oxidation process.

Benzotriazole (BTA) is a recalcitrant contaminant that is widely distributed in aquatic environments. This study explored the effectiveness of sulfate radical-based advanced oxidation process in degrading BTA (SR-AOP). The sulfate radical was generated by heat activation of persulfate (PS). Our results show alkaline pH promoted the BTA degradation. The solution pH also affected the speciation of total radicals. Sulfate radical ( S O 4 ⋅ - ) predominated at acidic pH while hydroxyl radical (HO•) predominated at basic pH. High temperature, high PS concentration and low BTA concentration promoted the BTA degradation. Influence of water matrix constituents on the reaction kinetics was assessed. We found that ≤10 mM of Cl- promoted the reaction, but 100 mM Cl- inhibited it. H C O 3 - was similar to Cl-. Br- and C O 3 2 - inhibited the reaction while S O 4 2 - did not affect the reaction. N O 3 - of ≤10 mM did not affect the reaction, but 100 mM of N O 3 - inhibited it. Eleven degradation intermediates were identified using ultra-high solution Orbitrap mass spectrometry. Based on the intermediates identified, possible reaction pathways were proposed. Overall, SR-AOP can effectively mineralize BTA, but water matrix constituents greatly influenced the reaction kinetics and thus should be carefully considered for its practical application. Abbreviations: BTA, benzotriazole; PS, persulfate; PMS, peroxymonosulfate; SPC, sodium percarbonate; AOP, advanced oxidation process; PS-AOP, persulfate-based advanced oxidation process; SR-AOP, sulfate radical-based advanced oxidation process; TAP, thermally activated persulfate; TOC, total organic carbon; TBA, tert-butyl alcohol.

Protecting Copper Oxidation State via Intermediate Confinement for Selective CO2 Electroreduction to C2+ Fuels.

Selective and efficient catalytic conversion of carbon dioxide (CO2) into value-added fuels and feedstocks provides an ideal avenue to high-density renewable energy storage. An impediment to enabling deep CO2 reduction to oxygenates and hydrocarbons (e.g., C2+ compounds) is the difficulty of coupling carbon-carbon bonds efficiently. Copper in the +1 oxidation state has been thought to be active for catalyzing C2+ formation, whereas it is prone to being reduced to Cu0 at cathodic potentials. Here we report that catalysts with nanocavities can confine carbon intermediates formed in situ, which in turn covers the local catalyst surface and thereby stabilizes Cu+ species. Experimental measurements on multihollow cuprous oxide catalyst exhibit a C2+ Faradaic efficiency of 75.2 ± 2.7% at a C2+ partial current density of 267 ± 13 mA cm-2 and a large C2+-to-C1 ratio of ∼7.2. Operando Raman spectra, in conjunction with X-ray absorption studies, confirm that Cu+ species in the as-designed catalyst are well retained during CO2 reduction, which leads to the marked C2+ selectivity at a large conversion rate.

Changes in activation energy and kinetics of heat-activated persulfate oxidation of phenol in response to changes in pH and temperature.

Persulfate (peroxydisulfate, S2O82-) is the newest oxidant used for the in situ chemical oxidation (ISCO) remediation of soil and groundwater. The present study investigated impacts of solution pH, temperature, and persulfate concentration on the reaction rate constant (k1), activation energy (Ea), and reaction order of the heat-activated persulfate process. Phenol was chosen as the model organic contaminant. As temperature increased from 30 °C to 70 °C, k1 exhibited a significant increase from 0.003 h-1∼0.962 h-1 (pH 1.3-13.9) to 1.184 h-1∼9.91 h-1 (pH 1.3-13.9), which corroborated with the activation of persulfate using heat. As pH increased from 1.3 to 13.9, k1 exhibited a 4.3-fold increase at 70 °C and a 320-fold increase at 30 °C, thereby suggesting that: 1) the phenol oxidation rate increased under alkaline conditions, and 2) the enhancement of reaction rate due to alkaline activation was more pronounced at a lower temperature. Increasing pH significantly reduced Ea from 139.7 ± 1.3 kJ/mol at pH 1.3 to 52.0 ± 3.3 kJ/mol at pH 13.9. In contrast to changing pH, increasing persulfate concentration from 20 to 320 mM significantly increased k1 but did not affect Ea. Changes in Ea suggest that persulfate oxidation of phenol experienced different reaction pathways or elementary reaction sequences as the pH changed from 1.3 to 13.9. In addition, the k1 and Ea data also suggest that a minimal pH threshold of ∼11 was required for the effective alkaline activation of persulfate.

Uncovering the role of elementary processes in network evolution.

The growth and evolution of networks has elicited considerable interest from the scientific community and a number of mechanistic models have been proposed to explain their observed degree distributions. Various microscopic processes have been incorporated in these models, among them, node and edge addition, vertex fitness and the deletion of nodes and edges. The existing models, however, focus on specific combinations of these processes and parameterize them in a way that makes it difficult to elucidate the role of the individual elementary mechanisms. We therefore formulated and solved a model that incorporates the minimal processes governing network evolution. Some contribute to growth such as the formation of connections between existing pair of vertices, while others capture deletion; the removal of a node with its corresponding edges, or the removal of an edge between a pair of vertices. We distinguish between these elementary mechanisms, identifying their specific role on network evolution.

Intergenerational transmission of educational attainment: Three levels of parent-child communication as mediators.

Although the intergenerational transmission of educational attainment has been confirmed by many researchers, its mechanism still remains controversial. Parent-child communication has been regarded as one of the important mediators. The present study primarily aimed to examine the potentially mediating role of parent-child communication in the transmission of educational attainment, based on a sample of 366 Chinese fifth and sixth graders. Parent-child communication was measured against the three levels of the parents' communication ability, the quality of the father-child and mother-child communications, and the relation between the two dyadic communications. The results duplicated the positive effect of parents' educational attainment on children's academic achievement. Moreover, it was found that parents' communication ability alone played a mediating role, and that the three levels of parent-child communication constructed a "mediator chain" between the parents' educational attainment and the children's academic achievement. Finally, the intergenerational transmission of educational attainment in China and the mediating role of the three levels of parent-child communication were discussed.

Birth cohort changes in Chinese adolescents' mental health.

In China, rapid economic growth and increasing social problems constitute two basic characteristics of contemporary social change. During the process of dramatic social change, an emerging question is how adolescents' mental health has changed across birth cohorts. The present paper reviews four studies of crosstemporal meta-analysis conducted by us. By meta-analysis of previous literature, we examined changes in mean scores on mental health measures over time (from the early 1990s to the mid-2000s). It was found that since the early 1990s, Chinese adolescents' mental health deteriorated across birth cohorts, shown in increased scores on the negative indicators of mental health (e.g. mental problems, anxiety, and depression), whereas self-esteem as a positive trait decreased. The dropping trend in Chinese adolescents' mental health could be attributed to social change, especially increasing social problems. Therefore, adequate attention must be paid to potential influences of social change on individuals' psychological development.

Wording effect leads to a controversy over the construct of the social dominance orientation scale.

Most investigations of individuals' social dominance orientation (SDO) have used the 16-item SDO scale developed by F. Pratto, J. Sidanius, L. M. Stallworth, and B. F. Malle (1994). The scale's authors believed it to be a unidimensional scale, but other researchers have found the scale has 2 or more factors. The present authors proposed a new hypothesis: The controversy of the scale structure was related to the wording effect of the scale. Based on a sample of Americans, Canadians, and Chinese, the present study indicated that what the scale measured was not only 1 trait of SDO, but also a negative-wording effect factor and that the scale structure was invariant across the 3 cultural groups. The existence of a wording effect reminds us to be cautious of the construct validity of the scale and interpretations of results.