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susanf金蟲 (小有名氣)
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電催化析氫的反應(yīng)動(dòng)力學(xué)取得重要研究進(jìn)展 已有1人參與
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從化石燃料逐步轉(zhuǎn)向可持續(xù)發(fā)展無(wú)污染的非化石能源是低碳可持續(xù)社會(huì)發(fā)展的必然趨勢(shì)。氫是理想的清潔能源之一，也是重要的化工原料，受到世界各國(guó)廣泛的重視。電解水制氫是實(shí)現(xiàn)工業(yè)化、廉價(jià)制備氫氣的重要手段。電催化析氫是目前最有前途的綠色制氫技術(shù)之一，是實(shí)現(xiàn)可再生清潔能源的重要途徑。然而，電催化析氫反應(yīng)過(guò)程中，緩慢的動(dòng)力學(xué)過(guò)程制約著催化反應(yīng)效率，增加活性位點(diǎn)的本征活性是加快催化反應(yīng)動(dòng)力學(xué)的有效策略，對(duì)于提升催化反應(yīng)的整體效率具有重要意義。但是催化活性中心的組成以及微觀動(dòng)力學(xué)研究仍然存在較大的爭(zhēng)議，迄今為止，還沒(méi)有統(tǒng)一的模型來(lái)解釋電催化析氫的微觀動(dòng)力學(xué)，例如ph、堿金屬離子和過(guò)渡金屬依賴的反應(yīng)動(dòng)力學(xué)。 華東師范大學(xué)張坤課題組使用zif-67衍生的納米結(jié)構(gòu)碳作為模型電催化劑，首先提供了確鑿的證據(jù)并證實(shí)界面sws以含水羥基絡(luò)合物的形式吸附在金屬{ohad·h2o@m+}（m+是過(guò)渡金屬或堿金屬陽(yáng)離子）是水活化（或離解）和隨后質(zhì)子還原的活性位點(diǎn)。sws中兩個(gè)o原子的空間相互作用可能是一種新型的弱相互作用，其強(qiáng)度介于氫鍵和化學(xué)共價(jià)鍵之間。此外，由于sws中兩個(gè)o原子的p軌道的空間重疊，形成了一個(gè)表面瞬態(tài)系綜，該系綜協(xié)同促進(jìn)了水和界面電子的激活以及納米尺度界面上的質(zhì)子轉(zhuǎn)移。應(yīng)該強(qiáng)調(diào)的是，這些動(dòng)態(tài)表面中間態(tài)（pbis）并不穩(wěn)定，這解釋了her（甚至oer和氧還原反應(yīng)）對(duì)微環(huán)境的極端敏感性，例如ph和陽(yáng)離子依賴性效應(yīng)。sws主導(dǎo)的表面瞬態(tài)概念可調(diào)節(jié)her的微觀動(dòng)力學(xué)，從而優(yōu)化整個(gè)電化學(xué)界面，從而提高活性，而不是僅優(yōu)化催化劑結(jié)構(gòu)，這對(duì)于設(shè)計(jì)更活躍的電化學(xué)界面以進(jìn)行涉及小分子（co2、co、n2、o2和h2）的儲(chǔ)能和轉(zhuǎn)化反應(yīng)至關(guān)重要。 作者強(qiáng)調(diào)了作為析氫催化活性中心的結(jié)構(gòu)水（sws）的概念與氫鍵水的概念完全不同，因?yàn)閟ws是兩個(gè)相鄰的水分子，主要通過(guò)兩個(gè)o原子的p軌道的空間重疊來(lái)結(jié)合，形成具有π鍵特征的局部化學(xué)鍵，由于空間軌道重疊，這為通過(guò)表面離域進(jìn)行電子轉(zhuǎn)移提供了一個(gè)替代通道。sws作為協(xié)同電子和質(zhì)子轉(zhuǎn)移的替代通道，同時(shí)作為活化水o-h鍵的活性位點(diǎn)，這一概念不僅可以為水環(huán)境中納米材料催化反應(yīng)的催化劑或電解質(zhì)的設(shè)計(jì)和選擇提供重要指導(dǎo)， 相關(guān)成果以activation of h2o tailored by interfacial electronic states at a nanoscale interface for enhanced electrocatalytic hydrogen evolution為題發(fā)表在《journal of the american chemical society au》（jacs au, 2022, doi: 10.1021/jacsau.2c00187）。全文鏈接有如下：https://pubs.acs.org/doi/10.1021/jacsau.2c00187 abstract: despite the fundamental and practical significance of the hydrogen evolution reaction (her), the reaction kinetics at the molecular level are not well-understood, especially in basic media. here, with zif-67-derived co-based carbon frameworks (co/ncs) as model catalysts, we systematically investigated the effects of different reaction parameters on the her kinetics and discovered that the her activity was directly dependent not on the type of nitrogen in the carbon framework but on the relative content of surface hydroxyl and water (oh╟/h2o) adsorbed on co active sites embedded in carbon frameworks. when the ratio of the oh╟/h2o was close to 1:1, the co/nc nanocatalyst showed the best reaction performance under the condition of high-ph electrolytes, e.g., an overpotential of only 232 mv at a current density of 10 ma cm╟2 in the 1 m koh electrolyte. we unambiguously identified that the structural water molecules (sws) in the form of hydrous hydroxyl complexes absorbed on metal centers {ohad·h2o@m+} were catalytic active sites for the enhanced her, where m+ could be transition or alkaline metal cations. different from the traditional hydrogen bonding of water, the hydroxyl (hydroxide) groups and water molecules in the sws were mainly bonded together via the spatial interaction between the p orbitals of o atoms, exhibiting features of a delocalized π-bond with a metastable state. these newly formed surface bonds or transitory states could be new weak interactions that synergistically promote both interfacial electron transfer and the activation of water (dissociation of o╟h bonds) at the electrode surface, i.e., the formation of activated h adducts (h*). the capture of new surface states not only explains ph-, cation-, and transition-metal-dependent hydrogen evolution kinetics but also provides completely new insights into the understanding of other electrocatalytic reductions involving other small molecules, including co2, co, and n2. 全文pdf免費(fèi)鏈接：https://pubs.acs.org/doi/10.1021/jacsau.2c00187 與結(jié)構(gòu)水（SWs）相關(guān)的幾篇核心文獻(xiàn)： （1）Yang, T.; Hu, X.; Shan, B.; Peng, B.; Zhou, J.; Zhang, K. Caged structural water molecules emit tunable brighter colors by topological excitation. Nanoscale 2021, 13 (35), 15058– 15066, 鏈接如下：https://pubs.rsc.org/en/content/articlelanding/2021/NR/D1NR02389F； （2）Zhou, J.; Yang, T.; Peng, B.; Shan, B.; Ding, M.; Zhang, K. Structural Water Molecules Confined in Soft and Hard Nanocavities as Bright Color Emitters. ACS Phys. Chem. Au 2022, 2 (1), 47– 58, 鏈接如下：https://pubs.acs.org/doi/10.1021/acsphyschemau.1c00020； （3）Yang, T.; Shan, B.; Huang, F.; Yang, S.; Peng, B.; Yuan, E.; Wu, P.; Zhang, K. P band intermediate state (PBIS) tailors photoluminescence emission at confined nanoscale interface. Commun. Chem. 2019, 2, 132, 鏈接如下：https://www.nature.com/articles/s42004-019-0233-1 |
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zhangkun232
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2樓2022-06-27 07:56:26
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3樓2022-07-06 22:40:19
zhangkun232
至尊木蟲 (著名寫手)
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