Electrical Transport Spectroscopy

Q&A

What was your role within the team?

Xiangfeng Duan: My primary role encompasses research design, addressing experimental challenges as they arise, interpreting results, and organizing and presenting findings.

Guangyan Zhong: My role focused on the fabrication and ETS measurement of platinum nanowire-based device under different conditions.

Chengzhang Wan: I was in charge of the electrochemical tests and Tafel analysis for HER kinetics on Pt nanowires under different pH values.

Sibo Wang: I helped with conducting the HER measurements and analysing the impact of pH on the Tafel slope for HER kinetics studies.

Tao Cheng: My role in this team is carrying out computational simulations to investigate the detailed reaction mechanism.

What were the biggest challenges in this project?

Guangyan Zhong: The primary challenge lies in deciphering the electrical signal from nano-devices into a vivid atomic portrait of reactions occurring at the Pt surface. This insight is then cross-validated with macroscopic-scale electrochemical measurements. Close collaboration and extensive discussions between experimental and simulation teams are crucial in overcoming this challenge and providing a comprehensive understanding of the reaction process.

Tao Cheng: The reaction mechanism under operando conditions remains poorly understood. On the simulation side, the existing methods are still not sufficiently accurate and efficient.

What different strengths did different people bring to the team?

Xiangfeng Duan: The research is driven by a highly interdisciplinary team comprising experts in nanoscale material synthesis, device fabrication, electrical measurements, and electrochemical characterizations. Professors Goddard and Alexandrova, along with their team, contribute essential theoretical expertise crucial for interpreting experimental findings accurately.

Chengzhang Wan: The development of electron transport spectroscopy (ETS) is a complex and gradual process, akin to the saying, "Rome was not built in a day". The technique's foundation was laid in the early 2010s by Professors Duan, Huang, and Dr Menging Ding, who initially used ETS to investigate surface-adsorbed anions on platinum surfaces and their impact on the kinetics of the oxygen reduction reaction. After that, Dr Zhihong Huang took over, shifting the focus to the hydrogen evolution reaction (HER). He discovered that ETS could be used to detect hydrogen adsorbed at different sites on platinum.

Further advancements were made by Dr Guangyan Zhong, who applied ETS to study the platinum surface under varying pH levels, revealing that the surface water's pKa influences the pH-dependent kinetics of HER. Dr Aamir Shah extended the application of ETS by using it to explore the synergistic effects of surface cation and hydroxyl adsorption on HER kinetics in alkaline conditions.

Throughout its development, ETS has proven to be an invaluable tool for elucidating the dynamic changes within the electrochemical double-layer structure. The journey of ETS from its inception to its current capabilities reflects a collaborative effort between experimental and theoretical researchers, who despite their differing viewpoints, have collectively accelerated the progress of this project through their intellectual exchanges and debates.

Why is this work so important and exciting?

Xiangfeng Duan: This work addresses a fundamental need: understanding molecular structures at electrochemical interfaces, which is crucial for advancing next-generation electrocatalysts vital for various renewable energy technologies. Conventional methods struggle to provide surface-specific insights, hindering progress. By developing a groundbreaking electrical transport spectroscopy approach, this research directly probes surface adsorbates, unravelling their critical role in electrochemical reactions. This breakthrough promises to bridge the gap between theory and experimentation, paving the way for the rational design of more efficient electrocatalysts for diverse electrochemical technologies.

Zisheng Zhang: This work not only captures key signals at the electrochemical interface in situ but also provides deep atomistic insights into solvation/electrolyte/adsorbate configurations. The great synergy between experiments and theories helps demystify multiple controversial topics in the field, such as cation effects and pH effects. Moreover, it presents a playground on which many more fundamental studies can be conducted.

Tao Cheng: Electrochemical reactions are crucial for developing suitable energy solutions. This study provides key insights into heterogeneous catalyst interfaces, operando reaction mechanisms, and offers guidelines for designing advanced catalysts.

William Goddard: The ETS technique from UCLA provides a unique measure of the H₃O⁺ at the surface. Normal experimental techniques cannot sample the ions close to the surface. Normal quantum mechanics (QM) cannot describe the 1000's of waters needed to describe all the waters within several nm of the surface, but Caltech's QM-trained ReaxFF could.

Where do you see the biggest impact of this technology/research being?

Xiangfeng Duan: The greatest impact of this research lies in its revolutionary approach to probing local chemical environments. Its application to other electrocatalytic systems promises deeper insights into adsorption/desorption processes and the influence of competing species. This advances our understanding of aqueous electrochemical reactions, with profound implications for fundamental science and technological applications. Specifically, the experimentally determined Pt-surface hydronium pKa offers a precise interpretation the lingering mystery of the pH-dependent HER kinetics on Pt surface, which is crucial for developing more efficient green hydrogen production technologies.

Sibo Wang: This technology/research provides a fundamental understanding at the molecular level of how the HER kinetics varies with pH, offering valuable guidance on the electrocatalysts improvement for renewable energy conversion.

William Goddard: The experiments validated the accuracy of the theoretical methods, which can now provide details about the surface reactions responsible for H₂ production and many other surface reactions.

How will this work be used in real life applications?

Xiangfeng Duan: The insights from our studies could facilitate the development of more efficient electrocatalysts with enhanced activity, selectivity, and durability, and this greatly impacts various renewable energy technologies, particularly in green hydrogen production and fuel cells.

Tao Cheng: This work facilitates the efficient conversion of sustainable energy sources like solar and wind into chemicals, enhancing their storage and utilization.

Sibo Wang: HER is a critical reaction in water electrolysis, which produces hydrogen as a promising energy carrier from renewable energy. This work offers a foundational comprehension of the pH-dependent HER kinetics, which could promote efficient hydrogen application to realize fossil fuel phase-out and limit climate change.

How do you see this work developing over the next few years, and what is next for this technology/research?

Xiangfeng Duan: We will apply our approach to study other technologically important reactions, including the oxygen evolution reaction (OER) and CO₂ reduction reactions (CO₂RR), which are central for renewable chemical fuel production; the hydrogen oxidation reaction (HOR) and oxygen reduction reaction (ORR) are essential for fuel cell technologies. We also have the aspiration to exploit the new insights developed from our study to guide the design of new electrocatalysts that could enable more efficient green hydrogen production or advanced fuel cells.

What inspires or motivates your team?

Xiangfeng Duan: My team finds inspiration in uncovering new insights and understanding, driving us to push the boundaries of knowledge. Additionally, the prospect of creating previously infeasible capabilities that benefit society drives our motivation. We strive to innovate and make meaningful contributions that address pressing challenges and improve the world around us.

What does good research culture look like or mean to you?

Chengzhang Wan: Maintaining curiosity about every observation, no matter how minor, while cautiously approaching interpretations. Our team values open dialogue and encourages frequent sharing of ideas with diversity; discussions are always welcome. It's important to consistently critique our work and question our assumptions by considering alternative explanations or reasons beyond our initial thoughts.

Tao Cheng: To me, good research culture is represented by close and deep collaboration, where team members share ideas and challenges openly, fostering an environment of mutual respect and collective growth.

Zisheng Zhang: In my view, a thriving research culture is where people of different expertise and backgrounds can learn from each other and grow together. It promotes a dynamic iteration process in which team members get to learn the strengths and limitations of each other so as to further modify the methods to push the frontier further until an agreement is reached and discoveries are made. Very fortunately, this is the culture of our team. I really enjoyed it throughout the collaboration, and our success is immensely owed to it.

What is the importance of collaboration in the chemical sciences?

Xiangfeng Duan: Collaboration in the chemical sciences drives innovation, accelerates discoveries, and enables the tackling of complex challenges beyond the scope of individual teams.

Sibo Wang: Collaboration in chemical sciences is essential for combining resources, integrating diverse expertise, inspiring innovation, and enhancing networking opportunities, which contribute to progress and breakthroughs in the field.

Tao Cheng: In the chemical sciences, collaboration is crucial because it allows for a multidimensional understanding and resolution of problems, accelerating and deepening the research process.

How are the chemical sciences making the world a better place?

Xiangfeng Duan: Chemistry is considered the central science that bridges all scientific disciplines. Chemistry is increasingly important today as we are facing increasing challenges such as resource depletion, pollution, and climate change. In this regard, the advancement in chemical science holds the key to unlocking the potential of renewable energy harvesting, storage and utilisation to secure a sustainable future.

Tao Cheng: Chemical sciences are making the world a better place by providing innovative materials and techniques that address global challenges and improve quality of life.

William Goddard: Sustainable H₂ production, clarified by this project, is essential to protecting our environment.

What advice would you give to a young person considering a career in chemistry?

Zisheng Zhang: Stay curious, as curiosity is the ultimate lasting motivation as one ventures into the realm of the unknown. Do not be satisfied by the status quo in the field or previous conclusions of your own, and stay critical. In a collaboration, be respectful and responsive, and don’t be too shy to learn from or to educate other members when needed.

Xiangfeng Duan: Building a solid foundation grants us the liberty to think critically, rationally and creatively, allowing one to tackle complex problems using the most fundamental scientific principles. Being curious and open-minded provides the freedom to think beyond boundaries, explore new ideas and push the frontiers of scientific discovery. Staying passionate ensures resilience in the face of challenges, a quality essential in original research.