Catalytic Materials


Electrocatalysts
The objective of our group is to develop efficient and robust catalytic systems to facilitate electrochemical energy conversion reactions such as carbon dioxide reduction and water splitting. An important aspect of our research hinges on the use of operando spectroscopic techniques to elucidate the mechanistic and structural aspects of these reactions. This allows us to establish the fundamental relationships between the structure/composition of the catalysts with their activities. This knowledge is then exploited to design and synthesize systems with improved functionality. We aim to synthesize catalysts from earth abundant materials, so that they can be used on a wide scale. Prototype electrolysis devices powered by solar energy to produce chemical feedstocks are engineered. The success of our research will be a critical step towards establishing an energy and chemical industry based on renewable feedstocks such as H2O and CO2.

Publications
[1] D. Ren, J. Fong, and B.S. Yeo. "The effects of currents and potentials on the selectivities of copper toward carbon dioxide electroreduction." Nature communications 9 (2018): 925.
[2] Y. Huang, Y. Deng, A.D. Handoko, G.K. Goh, and B.S. Yeo. "Rational Design of Sulfur‐Doped Copper Catalysts for the Selective Electroreduction of Carbon Dioxide to Formate." ChemSusChem 11 (2018): 320.
[3] Y. Huang, A.D. Handoko, P. Hirunsit, and B.S. Yeo. "Electrochemical reduction of CO2 using copper single-crystal surfaces: Effects of CO* coverage on the selective formation of ethylene." ACS Catalysis 7 (2017): 1749.
[4] D. Ren, B.S.H. Ang, and B.S. Yeo. "Tuning the selectivity of carbon dioxide electroreduction toward ethanol on oxide-derived CuxZn catalysts." ACS Catalysis 6 (2016): 8239.
[5] A.D. Handoko, C.W. Ong, Y. Huang, Z.G. Lee, L. Lin, G.B. Panetti, and B.S. Yeo. "Mechanistic insights into the selective electroreduction of carbon dioxide to ethylene on Cu2O-derived copper catalysts." The Journal of Physical Chemistry C 120 (2016): 20058.
[6] D. Ren, N.T. Wong, A.D. Handoko, Y. Huang, and B.S. Yeo. "Mechanistic insights into the enhanced activity and stability of agglomerated Cu nanocrystals for the electrochemical reduction of carbon dioxide to n-propanol." The Journal of Physical Chemistry Letters 7 (2015): 20.
[7] D. Ren, Y. Deng, A.D. Handoko, C.S. Chen, S. Malkhandi, and B.S. Yeo. "Selective electrochemical reduction of carbon dioxide to ethylene and ethanol on copper (I) oxide catalysts." ACS Catalysis 5 (2015): 2814.


Integrated nanocatalysts
In our research group, we carry out design and synthesis of integrated nanocatalysts for green fuel technology such as hydrogenation of CO2 to methanol. In preparing such new catalysts [1], various synthetic approaches have been developed in recent years. Normally, the primary catalytic phases are synthesized into monodisperse nanoparticles through wet chemical routes, while the hosting matrixes are often prepared as porous and/or hollow supports in solution with desired structural complexity and chemical functionality. In particular, integration of different catalytic components can be achieved in a step-by-step manner. Both top-down and bottom-up strategies have been employed in this type of synthetic architecture, benefiting from rapid advancement of nanoscience and nanotechnology as well as the maturing chemistry of materials. It is anticipated that structural and compositional requirements of such state-of-the-art nanocatalysts can be met at a higher level of sophistication and precision but at a much lower cost in future. Toward this goal, synthetic architecture of nanomaterials will continue to be an important field in future development of catalyst technology. Further investigation and invention of integrative methodology will lead to even more powerful catalysts, achieving an industrial scale of applications.

Publications
[1] H.C. Zeng. "Integrated nanocatalysts." Accounts of Chemical Research 46 (2012): 226.


Single-atom catalysts 
Innovative catalytic systems, with highly active and stable catalysts in the core, are the basis for any green fuel technology. Single-atom catalysts (or atomically dispersed metal catalysts), where all atoms are exposed as active sites for the reaction, have emerged as a new frontier in heterogeneous catalysis. These catalysts offer a promising way to utilize the precious metal elements more effectively, provided these isolated atoms are catalytically active and sufficiently stable. By applying basic principles in coordination chemistry and colloidal chemistry, we have developed, and will continue to develop more, single-atom catalysts with excellent stability and catalytic performance. We are also developing a broad range of robust single atoms supported on two-dimensional materials with high metal loadings via atomic layer deposition. In particular, this programme intends to identify single-atom alloy catalysts and carbide supported single-atom catalysts for methanol synthesis and beyond. The unique geometric and electronic structure of the single-atom catalysts hold the promise to revolutionize the Cu-Zn based catalyst that was developed over 50 years ago.

Publications
[1] B. Zhang, H. Asakura, J. Zhang, J. Zhang, S. De, and N. Yan. "Stabilizing a Platinum1 Single‐Atom Catalyst on Supported Phosphomolybdic Acid without Compromising Hydrogenation Activity." Angewandte Chemie International Edition 55 (2016): 8319.
[2] B. Zhang, H. Asakura, and N. Yan. "Atomically dispersed rhodium on self-assembled phosphotungstic acid: structural features and catalytic CO oxidation properties." Industrial & Engineering Chemistry Research 56 (2017): 3578.
[3] Z. Zhang, Y. Zhu, H. Asakura, B. Zhang, J. Zhang, M. Zhou, Y. Han, T. Tanaka, A. Wang, T. Zhang, and N. Yan. "Thermally stable single atom Pt/m-Al 2 O 3 for selective hydrogenation and CO oxidation." Nature Communications 8 (2017): 16100.
[4] T. Sun, B. Tian, J. Lu, and C. Su. "Recent advances in Fe (or Co)/N/C electrocatalysts for the oxygen reduction reaction in polymer electrolyte membrane fuel cells." Journal of Materials Chemistry A 5 (2017): 18933.
[5] Z. Qiu, H. Fang, A. Carvalho, A.S. Rodin, Y. Liu, S.J. Tan, M. Telychko, P. Lv, J. Su, Y. Wang, and A.H. Castro Neto. "Resolving the spatial structures of bound hole states in black phosphorus." Nano letters 17 (2017): 6935.
[6] Y. Liu, Z. Qiu, A. Carvalho, Y. Bao, H. Xu, S.J. Tan, W. Liu, A.H. Castro Neto, K.P. Loh, and J. Lu. "Gate-tunable giant stark effect in few-layer black phosphorus." Nano letters 17 (2017): 1970.
[7] S. Wickenburg, J. Lu, J. Lischner, H.Z. Tsai, A.A. Omrani, A. Riss, C. Karrasch, A. Bradley, H.S. Jung, R. Khajeh, and D. Wong. "Tuning charge and correlation effects for a single molecule on a graphene device." Nature communications 7 (2016): 13553