General Strategy to Fabricate Porous Co-Based Bimetallic Metal Oxide Nanosheets for High-Performance CO Sensing

Abstract

Two-dimensional (2D) porous bimetallic oxide nanosheets are attractive for high-performance gas sensing because of their porous structures, high surface areas, and cooperative effects. Nevertheless, it is still a huge challenge to synthesize these nanomaterials. Herein, we report a general strategy to fabricate porous cobalt-based bimetallic oxide nanosheets (Co–M–O NSs, M = Cu, Mn, Ni, and Zn) with an adjustable Co/M ratio and the homogeneous composition using metal–organic framework (MOF) nanosheets as precursors. The obtained Co–M–O NS possesses the porous nanosheet structure and ultrahigh specific surface areas (146.4–220.7 m2 g–1), which enhance the adsorption of CO molecules, support the transport of electrons, and expose abundant active sites for CO-sensing reaction. As a result, the Co–M–O NS exhibited excellent sensing performances including high response, low working temperature, fast response–recovery, good selectivity and stability, and ppb-level detection limitation toward CO. In particular, the Co–Mn–O NS showed the highest response of 264% to 100 ppm CO at low temperature (175 °C). We propose that the excellent sensing performance is ascribed to the specific porous nanosheet structure, the relatively highly active Co3+ ratio resulting from cation substitution, and large amounts of chemisorbed oxygen species on the surface. Such a general strategy can also be introduced to design noble-metal-free bimetallic metal oxide nanosheets for gas sensing, catalysis, and other energy-related fields.

2D materials: increscent quantum flatland with immense potential for applications

“…The sheets possess an ultra-high surface area of 220.7 m 2 g −1 , exposing abundant active sites. The sensor exhibited ppb level detection with room-temperature operation [ 94 ]. Jang et al developed subatomic level thick heterogeneous oxide SnO 2 /CoO x nanosheets for gas sensing.…”

Two‐Dimensional Nanomaterials for the Development of Efficient Gas Sensors: Recent Advances, Challenges, and Future Perspectives

“…However, there is still an immense task to prepare these porous 2D nanomaterials. Qin et al [174] reported a general scheme to prepare 2D porous structure cobalt-based bimetallic oxide sheets (Co-M-O NSs, M = Cu, Mn, Ni, and Zn) with tunable Co/M ratio with homogeneous composition [133] Reproduced with permission. [174] Reproduced with permission.…”

“…c) Temperature-dependent sensing response of Co−M−O NSs toward 100 ppm CO. d) Response and recovery time of Co−M−O NSs to 0.5−100 ppm CO. e) Dynamic response transition of Co−Mn−O NSs at 175 °C. TEM images of the f) Co−Cu−O NS, g) Co−Mn−O NS, h) Co−Ni−O NS, i) Co−Zn−O NS, j) XRD analyses of Co−Cu−O NS, Co−Mn−O NS, Co−Ni−O NS, and Co−Zn−O NS [174]. Reproduced with permission.…”

Multiple Strategies to Fabricate a Highly Stable 2D CuIICuI–Organic Framework with High Proton Conductivity

“…35 The large specific surface areas of 2D MOFs can provide more proton jumping sites, and the highly open interlayer channels also allow guest molecules carrying protons to enter, which synergistically improves proton transfer effectiveness. 36 Inspired by the studies above, we focused on the development of newer 2D MOFs as efficient proton conductors.…”

“…Thus, they have been applied in a wide variety of applications, − including use as proton conductors. − Two-dimensional (2D) MOFs have received an increasing amount of attention in recent years due to the exposure of the functional groups and the open interface . The large specific surface areas of 2D MOFs can provide more proton jumping sites, and the highly open interlayer channels also allow guest molecules carrying protons to enter, which synergistically improves proton transfer effectiveness . Inspired by the studies above, we focused on the development of newer 2D MOFs as efficient proton conductors.…”