Recently, Wang Lei-led research team of the School of Chemistry and Chemical Engineering(SCCE) of IMU has made progress in the research of photoelectrocatalysis of semiconductor and published in ACS Catalysis (IF:13.084) -an international journal in the field of catalysis- an article about solar neutral water splitting via photoelectrochemical etching, which is titled “Interface-Confined Surface Engineering via Photoelectrochemical Etching toward Solar Neutral Water Splitting”(URL：https://doi.org/10.1021/acscatal.1c05263). Ren Shijie, a Master of Science candidate of SCCE who was enrolled in 2021 and Sun Mao, another Master of Science candidate of SCCE who was enrolled in 2019, are co-authors of the article and Prof. Wang Lei who is with SCCE is the sole correspondent author of the article.
BVO is an ideal photo-anode. But it has serious photogenerated carrier recombination and photocorrosion, which confines its application in PEC water splitting. In recent years, it has been found that as cocatalyst, TMH, a transition metal oxide, can enhance the water oxidation kinetics of BVO. However, the interfacial recombination of BVO and the cocatalyst confines the water oxidation performance of PEC. Moreover, it is found in the present researches that alkaline water splitting can cause the corrosion of instrument and equipment and pollution of environment. So it is very important to achieve efficient and stable PEC water splitting in neutral environment to avoid alkaline environment. As is pointed in the article, the photolectrochemical etching can remove the interfacial charge recombination of semiconductor and transition metal oxide in the neutral environment and mediate charge transfer paths to achieve high-performance and stable operation of photo-anode of CoMoO4-x/BVO in a neutral environment.
Key point one: Influence of photolectrochemical etching on CoMoO4-x/BVO
There exists an amorphous layer of 2nm between the semiconductor and cocatalyst layer. The recombination of large amount of interfacial photogenerated carrier does not facilitate charge transfer. Via photoelectrochemical etching, barrier layer disappears; charge transfer paths are mediated and surface recombination of the semiconductor and cocatalyst is reduced. Moreover, there appear more amorphous phases and defects in the transition metal oxide-CoMoO4-x with high crystallization, and the active sites of cocatalyst are boosted.
Key point two: Activity and stability of PEC of CoMoO4-x/BVO with photoelectrochemical etching in a neutral environment
A- CoMoO4–x/BiVO4 after being photoelectrochemically etched exhibits a current density of 3.5 mA cm–2 at 1.23 VRHE with an excellent stability for 20 h in 0.5 M Na2SO4. The result shows that photochemical etching has prominent advantage in surface modification and provides the new paths to design the photo-anode system with excellent PEC performance in a neutral environment.
Key point three: Different roles of CoOx and MoOx in a neutral environment
The photoelectrochemical tests show that CoOx, as a transition metal oxide, provides active sites in a neutral environment, which makes photo-anode have excellent performance. The characterization of corrosion tests shows that MoOx has a good corrosion resistance performance in a neutral environment. As a passivation layer, MoOx can reduce surface recombination and protect the semiconductor from photocorrosion.
The above research was supported by the National Natural Science Foundation of China, Inner Mongolia Fund for Supporting Excellent Young Scientists, Inner Mongolia University Fund for Supporting Young Talents and Fund of IMU “Steed Plan” for Supporting Newly-joined Talents to Launch Scientific Researches.
A brief introduction to the correspondent author: Prof. Wang Lei, who is with SCCE of IMU and a PhD candidate supervisor, began her research work at the SCCE of IMU independently in December 2018. She has successively led the research projects from the National Natural Science Foundation of China, Inner Mongolia Fund for Supporting Excellent Young Scientists, Inner Mongolia University Fund for Supporting Young Talents, Lanzhou Institute of Chemical Physics(affiliated to Chinese Academy of Sciences) Fund for Distinguished Talents. In 2020, Wang Lei was selected as one of the members of “Grassland Talents” and won the “Ukli Award for Excellent Teachers of IMU”. Wang has published over 70 articles in the journals in the fields of chemistry and materials. Since its establishment in 2019, her research team has published 19 articles in the first section of SCI journals including 3 articles in Angew. Chem. Int. Ed. , 2 articles in ACS Catal., 3 articles in Appl. Catal B and some other articles in Adv. Energy Mater. and Nano Energy. One of them is frequently cited in ESI.
Website of Wang Lei’s research team: https://www.x-mol.com/groups/imu_wanglei