The recombination of photogenerated charge carriers severely limits the performance of photoelectrochemical (PEC) H 2 production. Here, we demonstrate that this limitation can be overcome by optimizing the charge tran...
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The recombination of photogenerated charge carriers severely limits the performance of photoelectrochemical (PEC) H 2 production. Here, we demonstrate that this limitation can be overcome by optimizing the charge transfer dynamics at the solid–liquid interface via molecular catalyst design. Specifically, the surface of a p-Si photocathode is modulated using molecular catalysts with different metal atoms and organic ligands to improve H 2 production performance. Co(pda-SO 3 H) 2 is identified as an efficient and durable catalyst for H 2 production through the rational design of metal centers and first/second coordination spheres. The modulation with Co(pda-SO 3 H) 2 , which contains an electron-withdrawing −SO 3 H group in the second coordination sphere, elevates the flat-band potential of the polished p-Si photocathode and nanoporous p-Si photocathode by 81 mV and 124 mV, respectively, leading to the maximized energy band bending and the minimized interfacial carrier transport resistance. Consequently, both the two photocathodes achieve the Faradaic efficiency of more than 95 % for H 2 production, which is well maintained during 18 h and 21 h reaction, respectively. This work highlights that the band-edge engineering by molecular catalysts could be an important design consideration for semiconductor–catalyst hybrids toward PEC H 2 production.
Limestone pore structure strongly influences dissolution and associated reactive transport. These effects are critical in limestone diagenesis and but also in engineering operations such as carbon capture and storage ...
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Limestone pore structure strongly influences dissolution and associated reactive transport. These effects are critical in limestone diagenesis and but also in engineering operations such as carbon capture and storage (CCS). However, detailed studies on how CO 2 -enriched (acidic) brine changes this pore structure at relevant reservoir storage conditions are very limited. Thus, to provide further quantitative information and more fundamental understanding about these key processes, we studied the dissolution patterns of a homogeneous, a fractured, and a vuggy limestone when flooded with CO 2 -saturated brine at representative storage conditions. The pore structured of these limestones showed drastically different responses to the acidic brine flood. As such, preferential channels surrounded by branched channels were formed in the homogeneous sample, while fractures became the main flow path in the fractured sample. In contrast, only one dominant channel formed in the vuggy sample, which resulted in a sharp permeability increase. These dissolution patterns reflect the associated Damköhler number, which significantly lower in the homogeneous, representing uniform dissolution. However, after injecting sufficient reactive fluid (1,000 PV), this uniform dissolution pattern transformed into a single preferential channel growth. Moreover, we conclude that increasing complexity of the pore geometry leads to more nonuniform dissolution. These dissolution patterns indicate the effect of initial pore structure on preferential channel growth and reaction transport. Our work provides key fundamental data for further quantifying limestone dissolution patterns in CCS, indicating that the CO 2 injection may cause the reactivation of geological faults and damage around wellbore, thus aids in the implementation of industrial-scale CCS. The impact of limestone pore structure on reactive transport was analyzed experimentally and computationally The dissolution patterns of homogeneous, f
Correction for ‘Epoxide ring-opening reaction promoted by ionic liquid reactivity: interplay of experimental and theoretical studies’ by Shengxin Chen et al., Catal. Sci. Technol., 2019, DOI: 10.1039/c9cy00953a.
Correction for ‘Epoxide ring-opening reaction promoted by ionic liquid reactivity: interplay of experimental and theoretical studies’ by Shengxin Chen et al., Catal. Sci. Technol., 2019, DOI: 10.1039/c9cy00953a.
Developing robust electrocatalysts and advanced devices is important for electrochemical carbon dioxide (CO 2 ) reduction toward the generation of valuable chemicals. We present herein a carbon-confined indium oxide e...
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Developing robust electrocatalysts and advanced devices is important for electrochemical carbon dioxide (CO 2 ) reduction toward the generation of valuable chemicals. We present herein a carbon-confined indium oxide electrocatalyst for stable and efficient CO 2 reduction. The reductive corrosion of oxidative indium to the metallic state during electrolysis could be prevented by carbon protection, and the applied carbon layer also optimizes the reaction intermediate adsorption, which enables both high selectivity and activity for CO 2 reduction. In a liquid-phase flow cell, the formate selectivity exceeds 90 % in a wide potential window from −0.8 V to −1.3 V vs. RHE. The continuous production of ca. 0.12 M pure formic acid solution is further demonstrated at a current density of 30 mA cm −2 in a solid-state electrolyte mediated reactor. This work provides significant concepts in the parallel development of electrocatalysts and devices for carbon-neutral technologies.
Herein, we have demonstrated the control over the structure of precatalysts to tune the properties of the active catalysts and their water oxidation activity. The reaction of K 3 [Fe(CN) 6 ] and Na 2 [Fe(CN) 5 (NO)] w...
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Herein, we have demonstrated the control over the structure of precatalysts to tune the properties of the active catalysts and their water oxidation activity. The reaction of K 3 [Fe(CN) 6 ] and Na 2 [Fe(CN) 5 (NO)] with Co(OH) 2 @CC produced precatalysts PC-1 and PC-2, respectively, with distinct structural and electronic features. The replacement of the −CN group with strong π-acceptor −NO modulates the electronic and atomic structure of PC-2. As a result, a facile electrochemical transformation of PC-2 into active catalyst Fe−Co(OH) 2 -Co(O)OH (AC-2) has been attained only in 15 CV cycles while 600 CV cycles are required for the electrochemical activation of PC-1 into AC-1. The X-ray absorption studies reveal the contraction of the Co−O and Fe−O bond in AC-2 because of the presence of a higher amount of Co 3+ and Fe 3+ than in AC-1. The high valent Co 3+ and Fe 3+ modulates the electronic properties of AC-2 and assists in the O−O bond formation, leading to the improved water oxidation activity.
Angesichts zunehmender ökologischer Probleme durch die massive Nutzung nicht biologisch abbaubarer, erdölbasierter Kunststoffe ist die Nachfrage nach neuen ökonomischen, umweltverträglichen und rec...
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Angesichts zunehmender ökologischer Probleme durch die massive Nutzung nicht biologisch abbaubarer, erdölbasierter Kunststoffe ist die Nachfrage nach neuen ökonomischen, umweltverträglichen und recyclierbaren Kunststoffmaterialien hoch. Eine mögliche Alternative stellt die bioinspirierte Synthese mineralbasierter Hybridmaterialien dar. Hier stellen wir ein auf amorphem Calciumcarbonat (ACC) basierendes Hydrogel aus sehr kleinen ACC‐Nanopartikeln vor, die durch Polyacrylsäure physikalisch vernetzt sind. Das Hydrogel ist formbar, dehnbar und selbstheilend. Durch Trocknung lassen sich feste, freistehende und transparente Objekte mit bemerkenswerten mechanischen Eigenschaften erstellen. Der ursprüngliche Hydrogel‐Zustand kann durch Quellen in Wasser vollständig wiederhergestellt werden. Das Material kann auch als Matrix für ein thermochromes Material dienen. Das hier vorgestellte Material ist ein Beispiel für eine neue Klasse von Kunststoffmaterialien, die “Mineral‐Kunststoffe”.
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