Pub Date : 2024-09-01DOI: 10.1016/S1872-2067(24)60065-3
Propane dehydrogenation (PDH) on Ga/H-ZSM-5 catalysts is a promising reaction for propylene production, while the detail mechanism remains debatable. Ga2O22+ stabilized by framework Al pairs have been identified as the most active species in Ga/H-ZSM-5 for PDH in our recent work. Here we demonstrate a strong correlation between the PDH activity and a fraction of Ga2O22+ species corresponding to the infrared GaH band of higher wavenumber (GaHHW) in reduced Ga/H-ZSM-5, instead of the overall Ga2O22+ species, by employing five H-ZSM-5 supports sourced differently with comparable Si/Al ratio. This disparity in Ga2O22+ species stems from their differing capacity in completing the catalytic cycle. Spectroscopic results suggest that PDH proceeds via a two-step mechanism: (1) C–H bond activation of propane on H-Ga2O22+ species (rate determining step); (2) β-hydride elimination of adsorbed propyl group, which only occurs on active Ga2O22+ species corresponding to GaHHW.
{"title":"C–H bond activation of propane on Ga2O22+ in Ga/H-ZSM-5 and its mechanistic implications","authors":"","doi":"10.1016/S1872-2067(24)60065-3","DOIUrl":"10.1016/S1872-2067(24)60065-3","url":null,"abstract":"<div><p>Propane dehydrogenation (PDH) on Ga/H-ZSM-5 catalysts is a promising reaction for propylene production, while the detail mechanism remains debatable. Ga<sub>2</sub>O<sub>2</sub><sup>2+</sup> stabilized by framework Al pairs have been identified as the most active species in Ga/H-ZSM-5 for PDH in our recent work. Here we demonstrate a strong correlation between the PDH activity and a fraction of Ga<sub>2</sub>O<sub>2</sub><sup>2+</sup> species corresponding to the infrared GaH band of higher wavenumber (GaHHW) in reduced Ga/H-ZSM-5, instead of the overall Ga<sub>2</sub>O<sub>2</sub><sup>2+</sup> species, by employing five H-ZSM-5 supports sourced differently with comparable Si/Al ratio. This disparity in Ga<sub>2</sub>O<sub>2</sub><sup>2+</sup> species stems from their differing capacity in completing the catalytic cycle. Spectroscopic results suggest that PDH proceeds <em>via</em> a two-step mechanism: (1) C–H bond activation of propane on H-Ga<sub>2</sub>O<sub>2</sub><sup>2+</sup> species (rate determining step); (2) β-hydride elimination of adsorbed propyl group, which only occurs on active Ga<sub>2</sub>O<sub>2</sub><sup>2+</sup> species corresponding to GaHHW.</p></div>","PeriodicalId":9832,"journal":{"name":"Chinese Journal of Catalysis","volume":null,"pages":null},"PeriodicalIF":15.7,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142122655","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-01DOI: 10.1016/S1872-2067(24)60102-6
{"title":"S-scheme heterojunction with ultrafast interfacial electron transfer for artificial photosynthesis","authors":"","doi":"10.1016/S1872-2067(24)60102-6","DOIUrl":"10.1016/S1872-2067(24)60102-6","url":null,"abstract":"","PeriodicalId":9832,"journal":{"name":"Chinese Journal of Catalysis","volume":null,"pages":null},"PeriodicalIF":15.7,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142122653","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-01DOI: 10.1016/S1872-2067(24)60099-9
Designing a step-scheme (S-scheme) heterojunction photocatalyst with vacancy engineering is a reliable approach to achieve highly efficient photocatalytic H2 production activity. Herein, a hollow ZnO/ZnS S-scheme heterojunction with O and Zn vacancies (VO, Zn-ZnO/ZnS) is rationally constructed via ion-exchange and calcination treatments. In such a photocatalytic system, the hollow structure combined with the introduction of dual vacancies endows the adequate light absorption. Moreover, the O and Zn vacancies serve as the trapping sites for photo-induced electrons and holes, respectively, which are beneficial for promoting the photo-induced carrier separation. Meanwhile, the S-scheme charge transfer mechanism can not only improve the separation and transfer efficiencies of photo-induced carrier but also retain the strong redox capacity. As expected, the optimized VO, Zn-ZnO/ZnS heterojunction exhibits a superior photocatalytic H2 production rate of 160.91 mmol g–1 h–1, approximately 643.6 times and 214.5 times with respect to that obtained on pure ZnO and ZnS, respectively. Simultaneously, the experimental results and density functional theory calculations disclose that the photo-induced carrier transfer pathway follows the S‐scheme heterojunction mechanism and the introduction of O and Zn vacancies reduces the surface reaction barrier. This work provides an innovative strategy of vacancy engineering in S-scheme heterojunction for solar‐to‐fuel energy conversion.
设计具有空位工程的阶梯型(S-scheme)异质结光催化剂是实现高效光催化产生 H2 活性的可靠方法。本文通过离子交换和煅烧处理,合理地构建了具有 O 和 Zn 空位(VO,Zn-ZnO/ZnS)的中空 ZnO/ZnS S 型异质结。在这种光催化系统中,中空结构结合双空位的引入,使其具有足够的光吸收能力。此外,O 空位和 Zn 空位分别作为光诱导电子和空穴的捕获位点,有利于促进光诱导载流子分离。同时,S 型电荷转移机制不仅能提高光诱导载流子的分离和转移效率,还能保持较强的氧化还原能力。正如预期的那样,优化的 VO、Zn-ZnO/ZnS 异质结的光催化 H2 产率高达 160.91 mmol g-1 h-1,分别是纯 ZnO 和 ZnS 的约 643.6 倍和 214.5 倍。同时,实验结果和密度泛函理论计算表明,光诱导载流子转移途径遵循 S 型异质结机制,O 和 Zn 空位的引入降低了表面反应势垒。这项工作为太阳能到燃料的能量转换提供了一种在 S 型异质结中进行空位工程的创新策略。
{"title":"Vacancy engineering mediated hollow structured ZnO/ZnS S-scheme heterojunction for highly efficient photocatalytic H2 production","authors":"","doi":"10.1016/S1872-2067(24)60099-9","DOIUrl":"10.1016/S1872-2067(24)60099-9","url":null,"abstract":"<div><p>Designing a step-scheme (S-scheme) heterojunction photocatalyst with vacancy engineering is a reliable approach to achieve highly efficient photocatalytic H<sub>2</sub> production activity. Herein, a hollow ZnO/ZnS S-scheme heterojunction with O and Zn vacancies (V<sub>O, Zn</sub>-ZnO/ZnS) is rationally constructed <em>via</em> ion-exchange and calcination treatments. In such a photocatalytic system, the hollow structure combined with the introduction of dual vacancies endows the adequate light absorption. Moreover, the O and Zn vacancies serve as the trapping sites for photo-induced electrons and holes, respectively, which are beneficial for promoting the photo-induced carrier separation. Meanwhile, the S-scheme charge transfer mechanism can not only improve the separation and transfer efficiencies of photo-induced carrier but also retain the strong redox capacity. As expected, the optimized V<sub>O, Zn</sub>-ZnO/ZnS heterojunction exhibits a superior photocatalytic H<sub>2</sub> production rate of 160.91 mmol g<sup>–1</sup> h<sup>–1</sup>, approximately 643.6 times and 214.5 times with respect to that obtained on pure ZnO and ZnS, respectively. Simultaneously, the experimental results and density functional theory calculations disclose that the photo-induced carrier transfer pathway follows the S‐scheme heterojunction mechanism and the introduction of O and Zn vacancies reduces the surface reaction barrier. This work provides an innovative strategy of vacancy engineering in S-scheme heterojunction for solar‐to‐fuel energy conversion.</p></div>","PeriodicalId":9832,"journal":{"name":"Chinese Journal of Catalysis","volume":null,"pages":null},"PeriodicalIF":15.7,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142122551","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-01DOI: 10.1016/S1872-2067(24)60101-4
Heterojunction has been widely used in vibration-driven piezocatalysis for enhanced charges separation, while the weak interfaces seriously affect the efficiency during mechanical deformations due to prepared by traditional step-by-step methods. Herein, the intimate contact interfaces with shared S atoms are ingeniously constructed in SnS2/SnS anchored on porous carbon by effective interface engineering, which is in-situ derived from temperature-dependent self-transformation of SnS2. Benefiting from intimate contact interfaces, the piezoelectricity is remarkably improved due to the larger interfacial dipole moment caused by uneven distribution of charges. Importantly, vibration-induced piezoelectric polarization field strengthens the interfacial electric field to further promote the separation and migration of charges. The dynamic charges then transfer in porous carbon with high conductivity and adsorption for significantly improved piezocatalytic activity. The degradation efficiency of bisphenol A (BPA) is 6.3 times higher than SnS2 and H2 evolution rate is increased by 3.8 times. Compared with SnS2/SnS prepared by two-step solvothermal method, the degradation efficiency of BPA and H2 evolution activity are increased by 3 and 2 times, respectively. It provides a theoretical guidance for developing various multiphase structural piezocatalyst with strong interface interactions to improve the piezocatalytic efficiency.
{"title":"Interface engineering via temperature-dependent self-transformation on SnS2/SnS for enhanced piezocatalysis","authors":"","doi":"10.1016/S1872-2067(24)60101-4","DOIUrl":"10.1016/S1872-2067(24)60101-4","url":null,"abstract":"<div><p>Heterojunction has been widely used in vibration-driven piezocatalysis for enhanced charges separation, while the weak interfaces seriously affect the efficiency during mechanical deformations due to prepared by traditional step-by-step methods. Herein, the intimate contact interfaces with shared S atoms are ingeniously constructed in SnS<sub>2</sub>/SnS anchored on porous carbon by effective interface engineering, which is <em>in-situ</em> derived from temperature-dependent self-transformation of SnS<sub>2</sub>. Benefiting from intimate contact interfaces, the piezoelectricity is remarkably improved due to the larger interfacial dipole moment caused by uneven distribution of charges. Importantly, vibration-induced piezoelectric polarization field strengthens the interfacial electric field to further promote the separation and migration of charges. The dynamic charges then transfer in porous carbon with high conductivity and adsorption for significantly improved piezocatalytic activity. The degradation efficiency of bisphenol A (BPA) is 6.3 times higher than SnS<sub>2</sub> and H<sub>2</sub> evolution rate is increased by 3.8 times. Compared with SnS<sub>2</sub>/SnS prepared by two-step solvothermal method, the degradation efficiency of BPA and H<sub>2</sub> evolution activity are increased by 3 and 2 times, respectively. It provides a theoretical guidance for developing various multiphase structural piezocatalyst with strong interface interactions to improve the piezocatalytic efficiency.</p></div>","PeriodicalId":9832,"journal":{"name":"Chinese Journal of Catalysis","volume":null,"pages":null},"PeriodicalIF":15.7,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142122552","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-01DOI: 10.1016/S1872-2067(24)60097-5
The conversion of acetone derived from biomass to isobutene has attracted extensive attentions. In comparison with Brønsted acidic catalyst, Lewis acidic catalyst could exhibit a better catalytic performance with a higher isobutene selectivity. However, the catalyst stability remains a key problem for the long-running acetone conversion and the reasons for catalyst deactivation are poorly understood up to now. Herein, the deactivation mechanism of Lewis acidic Y/Beta catalyst during the acetone to isobutene conversion was investigated by various characterization techniques, including acetone-temperature-programmed surface reaction, gas chromatography-mass spectrometry, in situ ultraviolet-visible, and13C cross polarization magic angle spinning nuclear magnetic resonance spectroscopy. A successive aldol condensation and cyclization were observed as the main side-reactions during the acetone conversion at Lewis acidic Y sites. In comparison with the low reaction temperature, a rapid formation and accumulation of the larger cyclic unsaturated aldehydes/ketones and aromatics could be observed, and which could strongly adsorb on the Lewis acidic sites, and thus cause the catalyst deactivation eventually. After a simple calcination, the coke deposits could be easily removed and the catalytic activity could be well restored.
{"title":"Deactivation mechanism of acetone to isobutene conversion over Y/Beta catalyst","authors":"","doi":"10.1016/S1872-2067(24)60097-5","DOIUrl":"10.1016/S1872-2067(24)60097-5","url":null,"abstract":"<div><p>The conversion of acetone derived from biomass to isobutene has attracted extensive attentions. In comparison with Brønsted acidic catalyst, Lewis acidic catalyst could exhibit a better catalytic performance with a higher isobutene selectivity. However, the catalyst stability remains a key problem for the long-running acetone conversion and the reasons for catalyst deactivation are poorly understood up to now. Herein, the deactivation mechanism of Lewis acidic Y/Beta catalyst during the acetone to isobutene conversion was investigated by various characterization techniques, including acetone-temperature-programmed surface reaction, gas chromatography-mass spectrometry, <em>in situ</em> ultraviolet-visible, and<sup>13</sup>C cross polarization magic angle spinning nuclear magnetic resonance spectroscopy. A successive aldol condensation and cyclization were observed as the main side-reactions during the acetone conversion at Lewis acidic Y sites. In comparison with the low reaction temperature, a rapid formation and accumulation of the larger cyclic unsaturated aldehydes/ketones and aromatics could be observed, and which could strongly adsorb on the Lewis acidic sites, and thus cause the catalyst deactivation eventually. After a simple calcination, the coke deposits could be easily removed and the catalytic activity could be well restored.</p></div>","PeriodicalId":9832,"journal":{"name":"Chinese Journal of Catalysis","volume":null,"pages":null},"PeriodicalIF":15.7,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142122549","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-01DOI: 10.1016/S1872-2067(24)60107-5
Two-dimensional covalent organic frameworks (2D COFs) feature extended π-conjugation and ordered stacking sequence, showing great promise for high-performance photocatalysis. Periodic atomic frameworks of 2D COFs facilitate the in-plane photogenerated charge transfer, but the precise ordered alignment is limited due to the non-covalent π-stacking of COF layers, accordingly hindering out-of-plane transfer kinetics. Herein, we address a chiral induction method to construct a parallelly superimposed stacking chiral COF ultrathin shell on the support of SiO2 microsphere. Compared to the achiral COF analogues, the chiral COF shell with the parallel AA-stacking structure is more conducive to enhance the built-in electric field and accumulates photogenerated electrons for the rapid migration, thereby affording superior photocatalytic performance in hydrogen evolution from water splitting. Taking the simplest ketoenamine-linked chiral COF as a shell of SiO2 particle, the resulting composite exhibits an impressive hydrogen evolution rate of 107.1 mmol g–1 h–1 along with the apparent quantum efficiency of 14.31% at 475 nm. Furthermore, the composite photocatalysts could be fabricated into a film device, displaying a remarkable photocatalytic performance of 178.0 mmol m–2 h–1 for hydrogen evolution. Our work underpins the surface engineering of organic photocatalysts and illustrates the significance of COF stacking structures in regulating electronic properties.
{"title":"Boosting photocatalytic hydrogen evolution enabled by SiO2-supporting chiral covalent organic frameworks with parallel stacking sequence","authors":"","doi":"10.1016/S1872-2067(24)60107-5","DOIUrl":"10.1016/S1872-2067(24)60107-5","url":null,"abstract":"<div><p>Two-dimensional covalent organic frameworks (2D COFs) feature extended π-conjugation and ordered stacking sequence, showing great promise for high-performance photocatalysis. Periodic atomic frameworks of 2D COFs facilitate the in-plane photogenerated charge transfer, but the precise ordered alignment is limited due to the non-covalent π-stacking of COF layers, accordingly hindering out-of-plane transfer kinetics. Herein, we address a chiral induction method to construct a parallelly superimposed stacking chiral COF ultrathin shell on the support of SiO<sub>2</sub> microsphere. Compared to the achiral COF analogues, the chiral COF shell with the parallel AA-stacking structure is more conducive to enhance the built-in electric field and accumulates photogenerated electrons for the rapid migration, thereby affording superior photocatalytic performance in hydrogen evolution from water splitting. Taking the simplest ketoenamine-linked chiral COF as a shell of SiO<sub>2</sub> particle, the resulting composite exhibits an impressive hydrogen evolution rate of 107.1 mmol g<sup>–1</sup> h<sup>–1</sup> along with the apparent quantum efficiency of 14.31% at 475 nm. Furthermore, the composite photocatalysts could be fabricated into a film device, displaying a remarkable photocatalytic performance of 178.0 mmol m<sup>–2</sup> h<sup>–1</sup> for hydrogen evolution. Our work underpins the surface engineering of organic photocatalysts and illustrates the significance of COF stacking structures in regulating electronic properties.</p></div>","PeriodicalId":9832,"journal":{"name":"Chinese Journal of Catalysis","volume":null,"pages":null},"PeriodicalIF":15.7,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142122662","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-01DOI: 10.1016/S1872-2067(24)60100-2
Since the D-band center theory was proposed, it has been widely used in the fields of surface chemistry by almost all researchers, due to its easy understanding, convenient operation and relative accuracy. However, with the continuous development of material systems and modification strategies, researchers have gradually found that D-band center theory is usually effective for large metal particle systems, but for small metal particle systems or semiconductors, such as single atom systems, the opposite conclusion to the D-band center theory is often obtained. To solve the issue above, here we propose a bonding and anti-bonding orbitals stable electron intensity difference (BASED) theory for surface chemistry. The newly-proposed BASED theory can not only successfully explain the abnormal phenomena of D-band center theory, but also exhibits a higher accuracy for prediction of adsorption energy and bond length of intermediates on active sites. Importantly, a new phenomenon of the spin transition state in the adsorption process is observed based on the BASED theory, where the active center atom usually yields an unstable high spin transition state to enhance its adsorption capability in the adsorption process of intermediates when their distance is about 2.5 Å. In short, the BASED theory can be considered as a general principle to understand catalytic mechanism of intermediates on surfaces.
自 D-带中心理论提出以来,由于其简单易懂、操作方便、相对准确等特点,几乎被所有研究人员广泛应用于表面化学领域。然而,随着材料体系和改性策略的不断发展,研究人员逐渐发现,D-带中心理论通常对大金属颗粒体系有效,但对于小金属颗粒体系或半导体,如单原子体系,往往会得到与 D-带中心理论相反的结论。为了解决上述问题,我们在此提出了一种用于表面化学的成键和反键轨道稳定电子强度差(BASED)理论。新提出的 BASED 理论不仅能成功解释 D 带中心理论的异常现象,而且在预测活性位点上中间产物的吸附能和键长方面表现出更高的精度。重要的是,基于 BASED 理论观察到了吸附过程中的自旋转变态新现象,即在中间产物的吸附过程中,当它们的距离为 2.5 Å 左右时,活性中心原子通常会产生不稳定的高自旋转变态以增强其吸附能力。
{"title":"Why the abnormal phenomena of D-band center theory exist? A new BASED theory for surface catalysis and chemistry","authors":"","doi":"10.1016/S1872-2067(24)60100-2","DOIUrl":"10.1016/S1872-2067(24)60100-2","url":null,"abstract":"<div><p>Since the D-band center theory was proposed, it has been widely used in the fields of surface chemistry by almost all researchers, due to its easy understanding, convenient operation and relative accuracy. However, with the continuous development of material systems and modification strategies, researchers have gradually found that D-band center theory is usually effective for large metal particle systems, but for small metal particle systems or semiconductors, such as single atom systems, the opposite conclusion to the D-band center theory is often obtained. To solve the issue above, here we propose a bonding and anti-bonding orbitals stable electron intensity difference (BASED) theory for surface chemistry. The newly-proposed BASED theory can not only successfully explain the abnormal phenomena of D-band center theory, but also exhibits a higher accuracy for prediction of adsorption energy and bond length of intermediates on active sites. Importantly, a new phenomenon of the spin transition state in the adsorption process is observed based on the BASED theory, where the active center atom usually yields an unstable high spin transition state to enhance its adsorption capability in the adsorption process of intermediates when their distance is about 2.5 Å. In short, the BASED theory can be considered as a general principle to understand catalytic mechanism of intermediates on surfaces.</p></div>","PeriodicalId":9832,"journal":{"name":"Chinese Journal of Catalysis","volume":null,"pages":null},"PeriodicalIF":15.7,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142122658","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-01DOI: 10.1016/S1872-2067(24)60106-3
Developing Cu single-atom catalysts (SACs) with well-defined active sites is highly desirable for producing CH4 in the electrochemical CO2 reduction reaction and understanding the structure-property relationship. Herein, a new graphdiyne analogue with uniformly distributed N2-bidentate (note that N2-bidentate site = N^N-bidentate site; N2 ≠ dinitrogen gas in this work) sites are synthesized. Due to the strong interaction between Cu and the N2-bidentate site, a Cu SAC with isolated undercoordinated Cu-N2 sites (Cu1.0/N2-GDY) is obtained, with the Cu loading of 1.0 wt%. Cu1.0/N2-GDY exhibits the highest Faradaic efficiency (FE) of 80.6% for CH4 in electrocatalytic reduction of CO2 at −0.96 V vs. RHE, and the partial current density of CH4 is 160 mA cm−2. The selectivity for CH4 is maintained above 70% when the total current density is 100 to 300 mA cm−2. More remarkably, the Cu1.0/N2-GDY achieves a mass activity of 53.2 A/mgCu toward CH4 under −1.18 V vs. RHE. In situ electrochemical spectroscopic studies reveal that undercoordinated Cu-N2 sites are more favorable in generating key *COOH and *CHO intermediate than Cu nanoparticle counterparts. This work provides an effective pathway to produce SACs with undercoordinated Metal-N2 sites toward efficient electrocatalysis.
开发具有明确活性位点的铜单原子催化剂(SAC),对于在电化学二氧化碳还原反应中生成 CH4 以及了解其结构-性能关系非常有帮助。本文合成了一种新的石墨二炔类似物,它具有均匀分布的 N2-二价(注意 N2-二价位点 = N^N-二价位点;在本文中 N2≠二氮气)位点。由于 Cu 与 N2 键合位点之间的相互作用很强,因此得到了一种具有孤立的欠配位 Cu-N2 位点的 Cu SAC(Cu1.0/N2-GDY),Cu 的负载量为 1.0 wt%。Cu1.0/N2-GDY 在 -0.96 V 对 RHE 的电压条件下,对 CH4 的电催化还原 CO2 的法拉第效率(FE)最高,达到 80.6%,CH4 的部分电流密度为 160 mA cm-2。当总电流密度为 100 至 300 mA cm-2 时,对 CH4 的选择性保持在 70% 以上。更显著的是,在 -1.18 V 对 RHE 条件下,Cu1.0/N2-GDY 对 CH4 的质量活度达到 53.2 A/mgCu。原位电化学光谱研究表明,欠配位的 Cu-N2 位点比对应的 Cu 纳米粒子更有利于生成关键的 *COOH 和 *CHO 中间体。这项工作为生产具有欠配位金属-N2 位点的 SACs 提供了有效途径,从而实现高效电催化。
{"title":"Cu single-atom electrocatalyst on nitrogen-containing graphdiyne for CO2 electroreduction to CH4","authors":"","doi":"10.1016/S1872-2067(24)60106-3","DOIUrl":"10.1016/S1872-2067(24)60106-3","url":null,"abstract":"<div><p>Developing Cu single-atom catalysts (SACs) with well-defined active sites is highly desirable for producing CH<sub>4</sub> in the electrochemical CO<sub>2</sub> reduction reaction and understanding the structure-property relationship. Herein, a new graphdiyne analogue with uniformly distributed N<sub>2</sub>-bidentate (note that N<sub>2</sub>-bidentate site = N^N-bidentate site; N<sub>2</sub> ≠ dinitrogen gas in this work) sites are synthesized. Due to the strong interaction between Cu and the N<sub>2</sub>-bidentate site, a Cu SAC with isolated undercoordinated Cu-N<sub>2</sub> sites (Cu<sub>1.0</sub>/N<sub>2</sub>-GDY) is obtained, with the Cu loading of 1.0 wt%. Cu<sub>1.0</sub>/N<sub>2</sub>-GDY exhibits the highest Faradaic efficiency (FE) of 80.6% for CH<sub>4</sub> in electrocatalytic reduction of CO<sub>2</sub> at −0.96 V <em>vs.</em> RHE, and the partial current density of CH<sub>4</sub> is 160 mA cm<sup>−2</sup>. The selectivity for CH<sub>4</sub> is maintained above 70% when the total current density is 100 to 300 mA cm<sup>−2</sup>. More remarkably, the Cu<sub>1.0</sub>/N<sub>2</sub>-GDY achieves a mass activity of 53.2 A/mg<sub>Cu</sub> toward CH<sub>4</sub> under −1.18 V <em>vs.</em> RHE. <em>In situ</em> electrochemical spectroscopic studies reveal that undercoordinated Cu-N<sub>2</sub> sites are more favorable in generating key *COOH and *CHO intermediate than Cu nanoparticle counterparts. This work provides an effective pathway to produce SACs with undercoordinated Metal-N<sub>2</sub> sites toward efficient electrocatalysis.</p></div>","PeriodicalId":9832,"journal":{"name":"Chinese Journal of Catalysis","volume":null,"pages":null},"PeriodicalIF":15.7,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142122665","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-01DOI: 10.1016/S1872-2067(24)60093-8
Hematite (α-Fe2O3) constitutes one of the most promising photoanode materials for oxygen evolution reaction (OER). Recent research on Fe2O3 have found a fast OER rate dependence on surface hole density, suggesting a multisite reaction pathway. However, the effect of heteroatom in Fe2O3 on the multisite mechanism is still poorly understood. Herein we synthesized Fe2O3 on Ti substrates (Fe2O3/Ti) to study the oxygen intermediates of OER by light-dark electrochemical scans. We identified the Fe-OH species disappeared and Ti-OH intermediates appeared on Fe2O3/Ti when pH = 11−14, which significantly improved the OER performance of Fe2O3/Ti. Combined with the density functional theory calculations, we propose that Ti atom acts as cocatalyst site and captures proton from neighboring Fe-OH species under highly alkaline condition, thereby promoting the coupling of Fe=O and reducing the energy barrier of the non-electrochemical step. Our work provides a new insight into the role of heteroatom in OER multisite mechanism based on clarifying the reaction intermediates.
赤铁矿(α-Fe2O3)是最有前途的氧进化反应(OER)光阳极材料之一。最近对 Fe2O3 的研究发现,OER 的快速速率与表面空穴密度有关,这表明存在多位点反应途径。然而,人们对 Fe2O3 中的杂原子对多位点机制的影响仍知之甚少。在此,我们在钛基底上合成了 Fe2O3(Fe2O3/Ti),并通过光-暗电化学扫描研究了 OER 的氧中间产物。我们发现当 pH = 11-14 时,Fe2O3/Ti 上的 Fe-OH 物种消失,Ti-OH 中间体出现,这显著提高了 Fe2O3/Ti 的 OER 性能。结合密度泛函理论计算,我们认为在高碱性条件下,Ti 原子作为协同催化剂位点,从邻近的 Fe-OH 物种中捕获质子,从而促进了 Fe=O 的耦合,降低了非电化学步骤的能垒。我们的研究在阐明反应中间产物的基础上,对异质原子在 OER 多位点机理中的作用提出了新的见解。
{"title":"The role of titanium at the interface of hematite photoanode in multisite mechanism: Reactive site or cocatalyst site?","authors":"","doi":"10.1016/S1872-2067(24)60093-8","DOIUrl":"10.1016/S1872-2067(24)60093-8","url":null,"abstract":"<div><p>Hematite (α-Fe<sub>2</sub>O<sub>3</sub>) constitutes one of the most promising photoanode materials for oxygen evolution reaction (OER). Recent research on Fe<sub>2</sub>O<sub>3</sub> have found a fast OER rate dependence on surface hole density, suggesting a multisite reaction pathway. However, the effect of heteroatom in Fe<sub>2</sub>O<sub>3</sub> on the multisite mechanism is still poorly understood. Herein we synthesized Fe<sub>2</sub>O<sub>3</sub> on Ti substrates (Fe<sub>2</sub>O<sub>3</sub>/Ti) to study the oxygen intermediates of OER by light-dark electrochemical scans. We identified the Fe-OH species disappeared and Ti-OH intermediates appeared on Fe<sub>2</sub>O<sub>3</sub>/Ti when pH = 11−14, which significantly improved the OER performance of Fe<sub>2</sub>O<sub>3</sub>/Ti. Combined with the density functional theory calculations, we propose that Ti atom acts as cocatalyst site and captures proton from neighboring Fe-OH species under highly alkaline condition, thereby promoting the coupling of Fe=O and reducing the energy barrier of the non-electrochemical step. Our work provides a new insight into the role of heteroatom in OER multisite mechanism based on clarifying the reaction intermediates.</p></div>","PeriodicalId":9832,"journal":{"name":"Chinese Journal of Catalysis","volume":null,"pages":null},"PeriodicalIF":15.7,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142122661","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-01DOI: 10.1016/S1872-2067(24)60105-1
Defect engineering has become a promising approach to improve the performance of hydrogen evolution reaction (HER) catalysts. Non-noble transition metal-based catalysts (TMCs) have shown significant promise as effective alternatives to traditional platinum-group catalysts, attracting considerable attention. However, the industrial application of TMCs in electrocatalytic hydrogen production necessitates further optimization to boost both catalytic activity and stability. This review comprehensively examines the types, fabrication methods, and characterization techniques of various defects that enhance catalytic HER activity. Key advancements include optimizing defect concentration and distribution, coupling heteroatoms with vacancies, and leveraging the synergy between bond lengths and defects. In-depth discussions highlight the electronic structure and catalytic mechanisms elucidated through in-situ characterization and density functional theory calculations. Additionally, future directions are identified, exploring novel defect types, emphasizing precision synthesis methods, industrial-scale preparation techniques, and strategies to enhance structural stability and understanding the in-depth catalytic mechanism. This review aims to inspire further research and development in defect-engineered HER catalysts, providing pathways for high efficiency and cost-effectiveness in hydrogen production.
缺陷工程已成为提高氢进化反应(HER)催化剂性能的一种前景广阔的方法。作为传统铂族催化剂的有效替代品,非贵金属基催化剂(TMCs)已显示出巨大的发展前景,引起了广泛关注。然而,TMCs 在电催化制氢中的工业应用需要进一步优化,以提高催化活性和稳定性。本综述全面探讨了可提高催化氢氧活性的各种缺陷的类型、制造方法和表征技术。主要进展包括优化缺陷浓度和分布、将杂原子与空位耦合,以及利用键长和缺陷之间的协同作用。深入的讨论突出了通过原位表征和密度泛函理论计算阐明的电子结构和催化机制。此外,还确定了未来的研究方向,探讨了新型缺陷类型,强调了精密合成方法、工业规模制备技术以及增强结构稳定性和深入了解催化机理的策略。本综述旨在激发对缺陷工程 HER 催化剂的进一步研究和开发,为高效、经济地制氢提供途径。
{"title":"Perfecting HER catalysts via defects: Recent advances and perspectives","authors":"","doi":"10.1016/S1872-2067(24)60105-1","DOIUrl":"10.1016/S1872-2067(24)60105-1","url":null,"abstract":"<div><p>Defect engineering has become a promising approach to improve the performance of hydrogen evolution reaction (HER) catalysts. Non-noble transition metal-based catalysts (TMCs) have shown significant promise as effective alternatives to traditional platinum-group catalysts, attracting considerable attention. However, the industrial application of TMCs in electrocatalytic hydrogen production necessitates further optimization to boost both catalytic activity and stability. This review comprehensively examines the types, fabrication methods, and characterization techniques of various defects that enhance catalytic HER activity. Key advancements include optimizing defect concentration and distribution, coupling heteroatoms with vacancies, and leveraging the synergy between bond lengths and defects. In-depth discussions highlight the electronic structure and catalytic mechanisms elucidated through <em>in-situ</em> characterization and density functional theory calculations. Additionally, future directions are identified, exploring novel defect types, emphasizing precision synthesis methods, industrial-scale preparation techniques, and strategies to enhance structural stability and understanding the in-depth catalytic mechanism. This review aims to inspire further research and development in defect-engineered HER catalysts, providing pathways for high efficiency and cost-effectiveness in hydrogen production.</p></div>","PeriodicalId":9832,"journal":{"name":"Chinese Journal of Catalysis","volume":null,"pages":null},"PeriodicalIF":15.7,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142122654","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}