Direct Thermochemical CO₂ Reduction to Reduced Graphene Oxide-like Nanomaterials: Implications for Environmental and Energy Storage and Conversion Applications

Abstract

CO2 capture and conversion to value-added products have seen continued advancement in recent years through electrochemical and thermochemical routes. In this work, we have adapted a facile and potentially scalable thermochemical reduction technique that directly reduces CO2 to different-quality reduced graphene oxide (rGO) solids. Several characterization techniques have been undertaken to investigate the role of two- and three-dimensional copper catalytic substrates, reaction time, and CO2 humidity content on the characteristics of the prepared rGO. Growth for 1 h at 550 °C atop a uniform two-dimensional (2D) catalytic copper substrate under a humidified CO2 environment (0.14 gH2O/gCO2) attained rGO with low defect densities (0.36 × 1011 cm–2) and high domain (31.9 nm) and crystallite (3.32 nm) sizes. Detailed statistical Raman analyses over large areas confirm that the mean defect distance of the synthesized rGO samples is 16–20 nm, indicative of the intrinsic high quality attained. The degree of reduction in rGO based on C/O ratios from 4 to 8 suggests that operating conditions can be fine-tuned to attain different-quality rGO with different attributable macroproperties such as conductivity and hydrophilicity. The developed method of direct CO2 reduction to rGO can be further tuned to produce different quality, morphology, and yield of other high-value solid carbon-based materials for emerging and existing applications.

Fractal growth of a fern-like nanostructured Cu2O film electrode for electrochemical reduction of CO2 to ethanol

“…The acceleration of anthropogenic pollutant CO 2 gas to the surfeit level has highlighted the urgent need to develop techniques to circumvent the issue. [1][2][3][4] Reduction of CO 2 has been achieved by various methods including thermochemical, 5,6 photocatalytic, [7][8][9] electrochemical, [10][11][12] and photo-electrochemical. 13,14 CO 2 conversion to obtain value-added products by an electrochemical approach is regarded as a promising and cost-effective strategy to recycle it and simultaneously address the global energy demand.…”

A brief review of in situ spectroscopic methods and electrochemical sensors as essential evaluation tools for the electrochemical reduction of CO2 (ElRC)

“…1 Increasing levels of atmospheric carbon dioxide (CO 2 ) are believed to be a main contributing factor in global climate change. [2][3][4][5] Thus, the adverse climate conditions have expedited the research and technological applications of various conversion technologies including electrochemical, 6,7 photo electrochemical, 8,9 chemical, [10][11][12] biochemical, [13][14][15] photochemical [16][17][18] and thermochemical 19,20 with the goal of simultaneously generating a variety of fuel-like products and lowering atmospheric CO 2 concentrations. 21 Each of these technologies have advantages and disadvantages; however, electrochemical techniques have been shown to be very promising due to their favourable features such as low operating temperature and pressure, possibility of compact and exible design, and ease of scaling up applications.…”