Engineered 2-D Heterostructures for Electrocatalysis

Atomically thin layered transition metal dichalcogenides (TMDs) such as MoS 2 , WS 2 , MoSe 2 and WSe 2 have been emerging as the cutting edge in materials science and engineering, due to their interesting electronic properties. 1 These materials open up new opportunities for a variety of applications, including optoelectronics, energy conversion, and catalysis. To realize their potential device applications, it is highly desirable to achieve controllable growth of these layered nanomaterials, with tunable structure and morphology. TMDs exhibit promising catalytic properties for hydrogen generation and several approaches including defect engineering have been shown to increase the active catalytic sites. 2,3 2D heterostructures based on various 2D layered materials with distinct properties have been demonstrated to exhibit novel physicochemical properties for their potential application in electrocatalytic hydrogen production. Here we present some of our efforts on morphological and photo/electrocatalytic studies of engineered 2D nanomaterials and their heterostructures. 4-6 A seed-assisted chemical vapor transport (CVT) growth of ultra-thin triangular flakes of highly crystalline trigonal selenium (t-Se) oriented in (0001) direction, with lateral size >30 μm is demonstrated. 5,6 To study their promising photo-electrocatalytic properties and further realize the device applications, we employed a single-step CVT approach to grow selenene/WSe 2 heterostructures. Vertical heterostructures of bi-layer selenene and monolayer WSe 2 domains obtained via the CVT method are characterized by optical microscopy, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy. The micro electrocatalytic reactor fabricated with Se/WSe 2 heterostructure shows significantly improved HER activities upon shining the light. The work further extends to explore strain-engineered TMDs and their heterostructures towards efficient electrocatalytic hydrogen evolution reaction. References H. R. Gutiérrez, N. Perea-López, A. L. Elías, A. Berkdemir, B. Wang, R . Lv, F. López-Urías, V. H. Crespi, H. Terrones, M. Terrones, Nano Lett . 2013, 13 (8), 3447-3454. P.V. Sarma, T.V.Vineesh, R.Kumar, V.Sreepal, R.Prasannachandran, A.K. Singh, and M.M. Shaijumon, ACS Catalysis (2020), 10,6753–6762 P. V. Sarma, A. Kayal, C. H. Sarma, M. Thalakulam, J. Mitra, and M. M. Shaijumon, ACS Nano , 13, 10448-10455 (2019). R. Prasannachandran, T. V. Vineesh, A. Anil, B. M. Krishna and M. M. Shaijumon, ACS Nano , 12, 11511–11519 (2018). R. Prasannachandran, T. V. Vineesh, M.B.Lithin, R. Nandakishore, M. M. Shaijumon, Chem. Commun. , 56, 8623-8626 (2020). P.V. Sarma, N. Renjith et al., 2D Mater ., 9, 045004 (2022)