Advanced Functional Materials:复杂中空电解水催化剂的最新研究进展

研究背景

由可再生能源驱动的电解水制氢技术以所得氢气纯度高、零碳排放等优势被认为是理想的清洁制氢技术,但缓慢的析氢反应(HER)和析氧反应(OER)动力学严重制约了其大规模应用。因此,合理设计高效高稳定电催化剂对于加快电解水制氢技术的快速发展至关重要。复杂中空纳米结构作为一类重要的功能材料,具有大的比表面积、边界明确的孔隙结构和可调的传质速率等独特的结构优势,在电解水领域表现出良好的应用前景。

成果简介

近日,北京化工大学于乐教授课题组了复杂中空纳米结构在电解水领域的最新研究进展,通过系统地探讨基于结构控制和组分调控的设计策略,设计应用于高效电解水反应的复杂中空催化剂,并对其未来发展方向进行了展望。

图1. 复杂中空电解水催化剂的结构/组分设计策略。

图文解析

复杂中空电解水催化剂的结构设计策略

复杂中空催化剂的结构设计策略主要在外部几何结构、壳层结构单元和内部空间结构方面对中空材料形貌进行调控,以改善电催化性能。

Figure 2. a) Schematic illustration of the formation of Ni-Fe LDH nanocages with tunable shells via a self-templated method. b) FESEM and c) TEM images of Ni-Fe LDH DSNCs. d) STEM image and e) the corresponding linear distributions. f) CV curves of Ni-Fe LDH catalysts and carbon paper. g) η for different current densities.

多壳层复杂中空结构:图2为由超薄纳米片组装的可调壳层的Ni-Fe层状双氢氧化物(LDH)纳米笼用作高效碱性OER电催化剂。

Figure 3. a) Schematic representation of the formation of G@N-MoS2. b-d) HRTEM images of G@N-MoS2. e) HER polarization curves obtained in N2-saturated 0.10 M KOH solution. f) OER polarization curves obtained in O2-saturated 0.10 M KOH solution. g) Schematic representation of the electron transfer effects in G@N-MoS2 heterostructures toward improved electrocatalytic activities for OER and HER.

多腔室复杂中空结构:图3为三维介孔的石墨烯/氮掺杂硫化钼范德华异质结(G@N-MoS2)用作高效碱性HER和OER电催化剂。

Figure 4. a) Schematic illustration of the formation process of R-TMO with a necklace-like multi-shelled hollow structure. b) SEM image of R-NCO (Inset: the corresponding magnified image). c,d) TEM images of R-NCO. e) Schematic illustration of creating oxygen vacancy defects on the surface of NCO after reduction, which is applied as a bifunctional electrocatalyst for water splitting to produce H2 and O2.

多维度调控复杂中空结构:图4为富含氧缺陷的项链状多壳层中空尖晶石氧化物(R-TMO)用作高效碱性HER和OER电催化剂。

Figure 5. a) Schematic illustration of the synthetic process of RuIrOx nano-netcage. b-d) AC HAADF-STEM and magnified images of RuIrOx nano-netcages. Scale bar: 10, 5, and 2 nm. The inset of (d) shows the corresponding FFT image of the selected region. Normalized XANES spectra of RuIrOx measured at different electrode potentials at e) Ru K-edge and f) Ir L3-edge during the HER process under alkaline condition. g) Comparison of the ratios of effective surface for supported nanoparticles and the three-dimensional open nano-netcage structure.

开放式的复杂中空结构:图5为由超细纳米线交叉围成的三维开放空心RuIrOx纳米网箱结构实现高效全pH值全解水。

Figure 6. a) SEM and b) TEM images of macroporous ATO particles. c-f) STEM-based tomography with 3D intensity volume reconstruction of the ATO-SG280Δ-IrO2 (≈25 wt% Ir). c) Total (ATO and IrO2) 3D intensity volume derived from particle reprojection. d) Extracted ATO 3D intensity volume from a complete particle. e) Extracted IrO2 3D intensity volume from a complete particle. f) Extracted cross section of an IrO2-coated ATO microparticle from the 3D intensity volume. g) Catalytic activity of IrO2 nanoparticle-loaded microparticles templated by 280 nm (ATO-SG280Δ-IrO2) PMMA for ηOER = 300 mV. h) CVs after 75 cycles at a scan rate of 50 mV s−1.

开放的复杂中空结构作为载体负载活性物种:图6为大孔Sb掺杂SnO2微粒(ATO)内表面和外表面均匀负载IrO2纳米颗粒及其在高效OER中的应用。

Figure 7. a) TEM and b) HRTEM image of WS2 trilayers. c) the schematic of WS2@graphene superparticles. d) Schematic of the calculation of strain in WS2 nanosheets. e) Mass-normalized EPR spectra of the three WS2@graphene samples. f) Schematic of WS2 with strain and S-vacancies for the HER. g) Free energy versus the reaction coordinate of HER for the SV range of 0-25% and strain (S) range of 0-4%. h) Plot of overpotentials at 10 mA cm−2 as a function of the WS2 layer number (Inset: the schematic of the hopping of electrons from graphene to the outmost WS2 layer for driving the HER).

工程应变:图7为具有精确可调应变和S空位,以及富边缘位置的原子弯曲2H-WS2纳米片用作高效HER催化剂。

复杂中空电解水催化剂的组分调控策略

除结构设计外,组分调控对于复杂中空电催化剂的性能改善也至关重要。随着研究的深入,单纯的形貌设计已经不能满足催化性能的需求。因此,将结构控制和组分调控相结合更有利于优化中空材料的电催化性能。

Figure 8. a) Schematic illustration of the synthetic procedure of Pt5/HMCS. b,c) HAADF-STEM images (Inset: size distribution of the Pt clusters and magnified image of Pt cluster), and d) element mapping of a single Pt5/HMCS-5.08% particle obtained at 550 °C for 15 h. HER polarization curves of Pt5/HMCS-5.08% and commercial Pt/C (5 and 20 wt%) catalysts based on geometric area of the working electrode in e) 0.5 M H2SO4 and f) 1.0 M KOH.

空间限域:图8为中空碳球限域Pt团簇增强酸性和碱性HER性能。

Figure 9. a) Schematic illustration of the synthetic process for MCM@MoS2-Ni. b,c) FESEM and d) TEM images of the hierarchical MCM@MoS2-Ni nanofibers. e) Ni K-edge EXAFS spectra of MCM@MoS2-Ni and Ni foil. f) Experimental XANES spectra for MCM@MoS2-Ni and Ni foil. g) HER polarization curves for different catalysts in 0.5 M H2SO4. h) Capacitive Δj/2 as a function of the scan rate for MCM@MoS2-Ni, MCM@MoS2 and MoS2 catalysts.

空间限域:图9为镍单原子修饰生长在多通道碳纳米纤维支撑的分层MoS2纳米片以增强酸性HER性能。

Figure 10. a) TEM images of the Ni2P-NiP2 HNPs with an average wall thickness of 6 nm (the scale bars in the right side of (a) are 20 nm). b) SAED pattern of the Ni2P-NiP2 HNPs with polycrystalline rings corresponding to Ni2P (red rings) and NiP2 (blue rings). c) HRTEM image of the Ni2P-NiP2 HNPs.

界面工程:图10为空心Ni2P-NiP2纳米多晶上的界面电子转移诱导碱性HER和OER性能增强。

Figure 11. TEM images of a) CoS and b) 14.6% CeOx/CoS. c) HRTEM image of 14.6% CeOx/CoS (Inset: corresponding SAED pattern). d) Elemental mapping images of 14.6% CeOx/CoS. e) LSV curves of 14.6% CeOx/CoS, CoS, CeO2, ZIF-67, and Ir/C catalysts for the OER. f) Tafel plots for the OER. g) Chronopotentiometric curve of water splitting for CoS and 14.6% CeOx/CoS. h) Co 2p XPS spectra, i) Co2+/Co3+ molar ratios (red line) and overpotential (black line) at 10 mA cm-2 of CoS and CeOx/CoS. j) O 1s XPS spectra of CoS and 14.6% CeOx/CoS.

构造缺陷:图11为在中空CoS纳米笼表面生长CeOx纳米颗粒,以实现Co2+/Co3+比例的精准调控和活性缺陷位点的生成,从而提升碱性OER性能。

Figure 12. a) Schematic representation of the synthetic process of FeCoNi-HNTAs. b) FESEM image of FeCoNi-HNTAs (Inset: the corresponding magnified FESEM image with the scale bar of 200 nm). c) STEM and EDX elemental mapping images of FeCoNi-HNTAs. d) HRTEM image of FeCoNi-HNTAs. e-g) Digital photos demonstrating the bubble releasing behaviors on the surface of FeCoNi-HNTAs, FeCoNi-LDH-NWAs, and bare Ni foam for HER (Insets: the corresponding size distribution statistics of releasing bubbles). h-j) Gas bubble adhesive force measurements of FeCoNi-HNTAs, FeCoNi-LDH-NWAs and MoS2/Ni Foam. Scale bars: b) 2 μm; c) 100 nm; d) 5 nm; h-j) 2 mm.

相调控:图12 为空心复合纳米管阵列用于高效全解水。水合肼的诱导剂和电子供体作用,以及Fe, Co, Ni硫化物和MoS2之间的电子转移共同促进2H到1T’相的转变。1T’ MoS2和Fe, Co, Ni三种离子之间的协同效应是HER和OER本征催化活性提升的原因。

结论与展望

这篇综述从结构设计和组分调控两方面归纳总结了近年来复杂中空结构用作电解水催化剂的研究进展。受益于可调的壳层结构单元、内部空间结构和化学组成,复杂中空材料在除电解水以外的其他领域也表现出良好的应用前景,如金属-空气电池、燃料电池以及CO2电还原等。虽然复杂中空材料的设计取得了重要进展和瞩目的成就,但在进一步开发更高效的电解水催化剂方面仍然存在挑战。

1) 从合成的角度来看,目前大多数合成方法存在合成路径繁琐、试剂有害、模板稀缺等问题,生产成本高。因此,应该进一步发展经济、规模化的合成技术,以制备高活性高稳定性的复杂中空电催化剂。从硬/软模板法向自模板法或无模板法的转变是中空结构设计和组分优化的良好选择。

2) 从催化的角度来看,缓慢的电极反应动力学是电解水技术快速发展的主要障碍。因此,仍需要加强对化学反应机理的研究以更好地理解电极结构与电催化性能之间的关系,为构筑高效复杂中空电解水催化剂提供方向。

3) 发展先进的原位表征技术和理论计算有助于进一步揭示电催化反应中的结构演化和真正活性物种,这对深入了解复杂中空纳米结构的催化行为和优化结构设计至关重要。

通讯作者介绍

于乐,北京化工大学教授,博士生导师。2018年入选科睿唯安跨学科领域全球高被引科学家名单,2019、2020连续两年入选科睿唯安化学、材料科学双领域全球高被引科学家名单。获2016、2017、2018年度Journal of Materials Chemistry A杰出审稿人。现任Energy & Environmental MaterialsGreen Energy & Environment、《物理化学学报》和《稀有金属》青年编委、《山东化工》编委。主要从事新型微纳米结构功能材料设计与合成,尤其是中空纳米功能材料的优化设计与合成探索,并研究功能纳米材料在电化学储能转化领域,如锂/钠离子电容器、电池、电催化等的应用。以第一作者/共同一作/通讯作者身份在Science Advances, Advanced Materials, Angewandte Chemie International Edition, Advanced Energy Materials, Advanced Functional Materials, Accounts of Chemical Research, Energy & Environmental Science, Nanoscale Advances等国际学术期刊发表了一系列文章,包括49篇ESI高被引论文,1篇ESI热点论文,11篇封面/内封底论文,1篇扉页论文和2篇VIP论文,SCI总引用19000余次,H-index为69。

课题组主页https://www.x-mol.com/groups/Yu_Le

文献来源

Recent Advances in Complex Hollow Electrocatalysts for Water Splitting

Yi Zhong Wang, Min Yang, Yi-Ming Ding, Nian-Wu Li, Le Yu*

Advanced Functional Materials

DOI: 10.1002/adfm.202108681

原文链接:https://onlinelibrary.wiley.com/doi/10.1002/adfm.202108681