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Instruments / Technical Area	Publication Details	Published
B07-B1-Versatile Soft X-ray beamline: High Throughput ES1 B18-Core EXAFS E02-JEM ARM 300CF	Atomically dispersed asymmetric cobalt electrocatalyst for efficient hydrogen peroxide production in neutral media Longxiang Liu , Liqun Kang , Jianrui Feng , David G. Hopkinson , Christopher S. Allen , Yeshu Tan , Hao Gu , Iuliia Mikulska , Veronica Celorrio , Diego Gianolio , Tianlei Wang , Liquan Zhang , Kaiqi Li , Jichao Zhang , Jiexin Zhu , Georg Held , Pilar Ferrer , David Grinter , June Callison , Martin Wilding , Sining Chen , Ivan Parkin , Guanjie He Nature Communications 15 DOI: 10.1038/s41467-024-48209-0 Diamond Proposal Number(s): [30614, 32058, 32035, 32117, 33466, 29271] Open Access Show Abstract ▼ Abstract: Electrochemical hydrogen peroxide (H2O2) production (EHPP) via a two-electron oxygen reduction reaction (2e- ORR) provides a promising alternative to replace the energy-intensive anthraquinone process. M-N-C electrocatalysts, which consist of atomically dispersed transition metals and nitrogen-doped carbon, have demonstrated considerable EHPP efficiency. However, their full potential, particularly regarding the correlation between structural configurations and performances in neutral media, remains underexplored. Herein, a series of ultralow metal-loading M-N-C electrocatalysts are synthesized and investigated for the EHPP process in the neutral electrolyte. CoNCB material with the asymmetric Co-C/N/O configuration exhibits the highest EHPP activity and selectivity among various as-prepared M-N-C electrocatalyst, with an outstanding mass activity (6.1 × 105 A gCo−1 at 0.5 V vs. RHE), and a high practical H2O2 production rate (4.72 mol gcatalyst−1 h−1 cm−2). Compared with the popularly recognized square-planar symmetric Co-N4 configuration, the superiority of asymmetric Co-C/N/O configurations is elucidated by X-ray absorption fine structure spectroscopy analysis and computational studies.	May 2024
E02-JEM ARM 300CF	Cathode–electrolyte interface modification by binder engineering for high-performance aqueous zinc-ion batteries Haobo Dong , Ruirui Liu , Xueying Hu , Fangjia Zhao , Liqun Kang , Longxiang Liu , Jianwei Li , Yeshu Tan , Yongquan Zhou , Dan J. L. Brett , Guanjie He , Ivan Parkin Advanced Science 334 DOI: 10.1002/advs.202205084 Diamond Proposal Number(s): [30614, 29809] Open Access Show Abstract ▼ Abstract: A stable cathode–electrolyte interface (CEI) is crucial for aqueous zinc-ion batteries (AZIBs), but it is less investigated. Commercial binder poly(vinylidene fluoride) (PVDF) is widely used without scrutinizing its suitability and cathode-electrolyte interface (CEI) in AZIBs. A water-soluble binder is developed that facilitated the in situ formation of a CEI protecting layer tuning the interfacial morphology. By combining a polysaccharide sodium alginate (SA) with a hydrophobic polytetrafluoroethylene (PTFE), the surface morphology, and charge storage kinetics can be confined from diffusion-dominated to capacitance-controlled processes. The underpinning mechanism investigates experimentally in both kinetic and thermodynamic perspectives demonstrate that the COO− from SA acts as an anionic polyelectrolyte facilitating the adsorption of Zn2+; meanwhile fluoride atoms on PTFE backbone provide hydrophobicity to break desolvation penalty. The hybrid binder is beneficial in providing a higher areal flux of Zn2+ at the CEI, where the Zn-Birnessite MnO2 battery with the hybrid binder exhibits an average specific capacity 45.6% higher than that with conventional PVDF binders; moreover, a reduced interface activation energy attained fosters a superior rate capability and a capacity retention of 99.1% in 1000 cycles. The hybrid binder also reduces the cost compared to the PVDF/NMP, which is a universal strategy to modify interface morphology.	Dec 2022
B07-B1-Versatile Soft X-ray beamline: High Throughput ES1 B18-Core EXAFS E01-JEM ARM 200CF E02-JEM ARM 300CF	Highly stable manganese oxide cathode material enabled by Grotthuss topochemistry for aqueous zinc ion batteries Fangjia Zhao , Jianwei Li , Arunabhiram Chutia , Longxiang Liu , Liqun Kang , Feili Lai , Haobo Dong , Xuan Gao , Yeshu Tan , Tianxi Liu , Ivan P. Parkin , Guanjie He Energy & Environmental Science 22 DOI: 10.1039/D3EE04161A Diamond Proposal Number(s): [32905, 29340, 32058] Open Access Show Abstract ▼ Abstract: The design and synthesis of manganese oxide-based materials with high-rate performance and long cycle life is a major challenge for aqueous zinc-ion batteries (AZIBs). This research reports the presence of a synergistic collaboration between vacancies, lattice water and nickel ions on enhancing the hydrated protons hopping via the Grotthuss mechanism for high-performance zinc ion batteries. The Grotthuss mechanism allows for the efficient transfer of a proton charge without the actual movement of the molecule over long distances, resulting in high ionic conductivity. NiMn3O7·3H2O achieves a capacity of 318 mA h g−1 under 200 mA g−1 and 121 mA h g−1 under 5 A g−1 with a retention of 91% after 4000 cycles. The relationship between the remarkable performance and Grotthuss topochemistry is investigated using techniques including synchrotron X-ray absorption spectroscopy and density functional theory. Protons prefer to bond with O2− ions on the Mn–O layer, and proton transfer is favoured in the presence of vacancies. The continuous hopping of protons within the host material induces periodic, temporary local structural changes in the lattice. This dynamic behaviour alters the energy barriers for ions intercalation and deintercalation. Nickel ions facilitate the ongoing mobility of hydrated protons via Grotthuss hopping by preserving the system's electrical neutrality, which counterbalances the dynamic changes caused by proton migration. This study provides insight into the Grotthuss conduction mechanism for the development of high-performance cathode materials in AZIBs.	Jan 2024
B07-B1-Versatile Soft X-ray beamline: High Throughput ES1	Hybrid Ni2P/CoP nanosheets as efficient and robust electrocatalysts for domestic wastewater splitting Yeshu Tan , Jianrui Feng , Liqun Kang , Longxiang Liu , Fangjia Zhao , Siyu Zhao , Dan J. L. Brett , Paul R. Shearing , Guanjie He , Ivan Parkin Energy & Environmental Materials DOI: 10.1002/eem2.12398 Diamond Proposal Number(s): [29340] Show Abstract ▼ Abstract: The development of low-cost, robust and efficient non-noble metal electrocatalysts is still a pursuit for the hydrogen evolution reaction (HER). Herein, a self-standing electrocatalyst, Ni2P/CoP nanosheet, was fabricated directly on three-dimensional Ni foams by two facile steps, which illustrated both high activity and stability for HER in different electrolytes. Benefiting from the porous structures of nanosheets with large specific surface area and the hybrid Ni2P/CoP, the as-prepared electrocatalyst presented remarkable HER with overpotentials of 65.2 mV and 87.8 mV to reach a current density of -10 mA cm-2 in neutral and alkaline media, respectively. Density function theory calculations revealed a lower activation energy of water dissociation and efficient HER steps of hybrid Ni2P/CoP nanosheets compared with mono CoP. The self-standing electrocatalyst maintained excellent chemical stability. Additionally, the HER process in domestic wastewater was realized with more impressive performance by using Ni2P/CoP nanosheets compared with commercial Pt/C. Hydrogen was continuously generated for 20 h in mildly alkaline dishwashing wastewater. This work provides a feasible way to fabricate non-noble metal and self-standing hybrid bimetallic phosphides for HER in neutral and alkaline media, showing great potential for efficient hydrogen production by re-utilizing wastewater resources.	Apr 2022
B07-C-Versatile Soft X-ray beamline: Ambient Pressure XPS and NEXAFS	Platinum-based self-standing electrocatalysts for efficient hydrogen evolution reaction Yeshu Tan Show Abstract ▼ Abstract: The hydrogen evolution reaction (HER) requires stable and effective platinum (Pt)-based electrocatalysts. Traditional Pt powdery electrocatalysts face problems of dispersion and dissolution during the electrode preparation process and HER process. This leads to poor durability under high current density, especially if aiming for future industrial applications. Thus, platinum-based self-standing electrocatalysts were developed in this thesis for efficient and durable HER. Furthermore, traditional platinum-based electrocatalysts have limitations in HER activity in neutral and alkaline medium due to sluggish water dissociation, limited diffusion of H⁺ and slow desorption of H*. Therefore, based on selected substrates, Pt nanocrystals were grown directly on substrate as self-standing electrocatalyst, exploring the tuning of electronic structure in both experimental and theoretical results. First, Pt nanocrystals in the form of "blackberries" on copper (Cu) foams with minimal loading served as a self-standing electrode and the synthesis was accomplished by an easy, low-temperature strategy. The interaction between Pt and Cu foam was studied, leading to materials with ultra-stability under high current density. Second, based on the interaction between Pt and Cu, phosphorus was introduced to modify the surface environment, further increasing the HER performance in neutral medium. Third, Ni₂P/CoP nanosheet was grown directly on nickel (Ni) foam, which was considered as an efficient self-standing electrocatalyst. The synergistic effect was explored between Ni₂P and CoP. Furthermore, the as-prepared electrocatalyst was applied to domestic wastewater for HER, widening the feasibility of HER in complicated electrolytes. Fourth, Pt nanocrystals were grown on the edge of the Ni₂P/CoP nanosheet, forming a unique heterostructure, as a self-standing electrocatalyst. The local electric field effect and electronic structure were both explored, illustrating the remarkable HER activity in alkaline medium. This thesis described the modification of Pt nanocrystals on selected substrates as self-standing electrocatalyst for efficient and stable HER process.	Apr 2023
B07-B1-Versatile Soft X-ray beamline: High Throughput ES1 E02-JEM ARM 300CF	Spectroscopic identification of active sites of oxygen-doped carbon for selective oxygen reduction to hydrogen peroxide Longxiang Liu , Liqun Kang , Arunabhiram Chutia , Jianrui Feng , Martyna Michalska , Pilar Ferrer , David Grinter , Georg Held , Yeshu Tan , Fangjia Zhao , Fei Guo , David Hopkinson , Christopher Allen , Yanbei Hou , Junwen Gu , Ioannis Papakonstantinou , Paul Shearing , Dan Brett , Ivan P. Parkin , Guanjie He Angewandte Chemie International Edition DOI: 10.1002/anie.202303525 Diamond Proposal Number(s): [29340, 32501, 30614, 29809, 32058] Open Access Show Abstract ▼ Abstract: The electrochemical synthesis of hydrogen peroxide (H2O2) via a two-electron (2e-) oxygen reduction reaction (ORR) process provides a promising alternative to replace the energy-intensive anthraquinone process. However, the development of efficient electrocatalysts is still facing lots of challenges like insufficient understanding of active sites. Herein, we develop a facile template-protected strategy to synthesize a highly active quinone-rich porous carbon catalyst (PCC) for H2O2 electrochemical production. The optimized PCC900 exhibits unprecedented activity and selectivity, of which the onset potential reaches 0.83 V vs. reversible hydrogen electrode in 0.1 M KOH and the H2O2 selectivity is over 95 % in a wide potential range. Comprehensive synchrotron-based near-edge X-ray absorption fine structure (NEXAFS) spectroscopy combined with electrocatalytic characterizations reveals the positive correlation between quinone content and 2e- ORR performance. The effectiveness of chair-form quinone groups as the most efficient active sites is highlighted by the molecule-mimic strategy and theoretical analysis.	Mar 2023
E02-JEM ARM 300CF	The edge effects boosting hydrogen evolution performance of platinum/transition bimetallic phosphide hybrid electrocatalysts Yeshu Tan , Jianrui Feng , Haobo Dong , Longxiang Liu , Siyu Zhao , Feili Lai , Tianxi Liu , Ying Bai , Ivan Parkin , Guanjie He Advanced Functional Materials DOI: 10.1002/adfm.202209967 Diamond Proposal Number(s): [30614, 29809, 32058] Open Access Show Abstract ▼ Abstract: Platinum (Pt) is regarded as a promising electrocatalyst for hydrogen evolution reaction (HER). However, its application in an alkaline medium is limited by the activation energy of water dissociation, diffusion of H+, and desorption of H*. Moreover, the formation of effective structures with a low Pt usage amount is still a challenge. Herein, guided by the simulation discovery that the edge effect can boost local electric field (LEF) of the electrocatalysts for faster proton diffusion, platinum nanocrystals on the edge of transition metal phosphide nanosheets are fabricated. The unique heterostructure with ultralow Pt amount delivered an outstanding HER performance in an alkaline medium with a small overpotential of 44.5 mV and excellent stability for 80 h at the current density of −10 mA cm−2. The mass activity of as-prepared electrocatalyst is 2.77 A mg−1Pt, which is 15 times higher than that of commercial Pt/C electrocatalysts (0.18 A mg−1Pt). The density function theory calculation revealed the efficient water dissociation, fast adsorption, and desorption of protons with hybrid structure. The study provides an innovative strategy to design unique nanostructures for boosting HER performances via achieving both synergistic effects from hybrid components and enhanced LEF from the structural edge effect.	Nov 2022

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