Interfaces in Photocatalysis, Electrocatalysis, and Photoelectrocatalysis

Background & Motivation

The environmentally-benign water cycle is one of the key energy-environmental cycles for a clean energy option in renewable energy conversion and storage. We aim to understand the structural and kinetics mechanisms of interfaces relevant to electrocatalysis, photocatalysis, and photoelectrocatalysis by developing in situ electrochemical interface-specific spectroscopy. We have also made efforts in interfacial engineering that help us improve catalytic efficiency and help us design new catalysts.  We will utilize our expertise in spectroscopy for deeper understandings of these catalytic structures and processes.


Another interest is that we develop interfacial catalysts in renewable energy conversion and storage. Both hydrogen and oxygen electrochemistry play a pivotal role in the water cycle, including hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) for electrolyzers as well as HER and hydrogen oxidation reaction (HOR) for metal-H batteries. At present, platinum-group metal (PGM) based materials are the most efficient electrocatalysts for the hydrogen and oxygen electrochemistry under acidic conditions, where few PGM-free electrocatalysts show comparable catalytic activity and stability. Therefore, it is of both fundamental and technological significance to develop highly competent and earth-abundant PGM-free electrocatalysts for both hydrogen and oxygen electrochemistry. Interface engineering is one of the promising strategies to develop efficient PGM-free electrocatalysts through modifying the catalytic activities and binding behaviors of reactants, intermediates, and products. Our studies are focused on modifications of interfaces of PGM-based catalysts for the improvement of hydrogen and oxygen electrochemistry.

Experimental Methods

  • Heterodyne-detection electronic sum frequency generation

  • Heterodyne-detection vibrational sum frequency generation 

  • Time-resolved electronic sum frequency generation

  • Time-resolved vibrational sum frequency generation

  • in situ electrochemistry Stimulated Raman spectroscopy

  • in situ electrochemistry vibrational sum frequency generation

Main Findings

  • Identification of surface states of GaP(100) photoelectrodes by combining azimuth-dependent ESFG spectroscopy with phase measurements for both n-type and p-type GaP(100) photoelectrodes. Surface states were found to originate from surface-charge-induced local states that carry different charges: negative for n-type and positive for p-type GaP.

  • Probing kinetics of surface electric fields and surface carrier population for n- and p-type GaP(100) photoelectrodes  by deploying time-resolved ESFG spectroscopy. Transient spectral signatures of the surface states showed that photoexcited electrons move toward the surface regions for p-type GaP, while photoexcited holes migrate to the surface regions for n-type GaP.

  • Development of interfacial catalysts for HOR and HER. We design and fabricate a novel interface catalyst of Ni and Co2N for hydrogen evolution reaction (HER) and hydrogen oxidation reaction (HOR). Hybridizations in the three elements of Ni-3d, N-2p, and Co-3d result in charge transfer in the interfacial junction of the Ni and Co2N materials

  • Interfacial sites for hydrogen energy. We have developed Co2N/Co interfacial materials, which exhibit bifunctional activity for hydrogen electrochemistry, rivaling the state-of-the-art Pt counterparts tested under similar conditions. It was found that Co2 N/Co interfacial sites not only possess optimal hydrogen adsorption energy but also facilitate water adsorption and dissociation on the catalyst surface.

  • Two-dimensional (2D) MXene-based interfacial electrocatalysts for hydrogen energy. We successfully immobilized transition-metal based NiMo nanoparticles (NPs) on 2D Ti3C2Tx surfaces, resulting in superior hydrogen evolution reaction (HER) and hydrogen oxidation reaction (HOR) activities in an alkaline media.

  • Interfacial charge transfer catalysts of non-precious transition metal electrocatalysts for hydrogen economy and battery. We exploit interface engineering to construct a novel interface catalyst of Ni3N and Co2N that exhibits superior bifunctional activity for hydrogen electrochemistry comparable to the state-of-the-art Pt catalyst, as well as high oxygen evolution reaction activity. Furthermore, the multifunctional Ni3N/CoN interface electrocatalysts demonstrate excellent applications in water splitting for H2 generation and a highly stable Swageloktype Ni−H battery for H2 utilization.

  • Fuzhan Song#, Tong Zhang#, Dexia Zhou#, Pengfei Sun, Zhou Lu*, Hongtao Bian*, Jingshuang Dang*, Hong Gao*, Yuqin Qian, Wei Li, Nan Jiang, Haley Dummer, Jeremy G. Shaw, Shutang Chen, Gugang Chen*, Yujie Sun*, Yi Rao*, ACS Materials Letter 2022, 4, 5, 967–977.


  • Tong Zhang#, Zhi-Chao Huang-Fu#, Yuqin Qian, Hong Gao*, Jesse Brown, and Yi Rao*, The Journal of Physical Chemistry C 2022, 126, 15, 6761–6772.


  • Tong Zhang, Yuqin Qian, Hong Gao*, Zhi-Chao Huang-Fu, Jesse Brown, and Yi Rao*, The Journal of Physical Chemistry C 2022, 126, 15, 6761–6772.

  • Tong Zhang, Shaun Debow, Fuzhan Song, Yuqin Qian, William R. Creasy, Brendan G. DeLacy, and, Yi Rao*, The Journal of Physical Chemistry Letters 2021, 12, 46, 11361–11370.


  • Kaixi Sun, Tong Zhang, Liming Tan, Dexia Zhou, Yuqin Qian, Xiaoxia Gao, Fahui Song*, Hongtao Bian*, Zhou Lu*, Jingshuang Dang, Hong Gao, Jeremy Shaw, Shutang Chen, Gugang Chen, and Yi Rao*, ACS Applied Material Interfaces 2020, 12 (26), 29357–29364.


  • Fuzhan Song, Wei Li, Jiaqi Yang, Guanqun Han, Tao Yan, Xi Liu, Yi Rao*, Peilin Liao*, Zhi Cao*, Yujie Sun*, ACS Energy Letters 2019, 4, 7, 1594-1601.

Representative Publications

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