RESUMEN
Electrochemical CO2 reduction (ECO2R) to value-added chemicals offers a promising approach to both mitigate CO2 emission and facilitate renewable energy conversion. We demonstrate a solar energy powered ECO2R system operating at a relatively large current density (57 mA cm-2) using In2O3 nanosheets (NSs) as the cathode and a commercial perovskite solar cell as the electricity generator, which achieves the high solar to formate energy conversion efficiency of 6.6 %. The significantly enhanced operative current density with a fair solar energy conversion efficiency on In2O3 NSs can be ascribed to their high activity and selectivity for formate production, as well as the fast kinetics for ECO2R. The Faradic efficiencies (FEs) of formate In2O3 NSs are all above 93 %, with the partial current density of formate ranging from 2.3 to 342 mA cm-2 in a gas diffusion flow cell, which is among the widest for formate production on In-based catalysts. In-situ Raman spectroscopy and density functional theory simulations reveal that the exceptional performances of formate production on In2O3 NSs originates from the presence of abundant low coordinated edge sites, which effectively promote the selective adsorption of *OCHO while inhibiting *H adsorption.
RESUMEN
Covalent organic frameworks (COFs) are promising photocatalysts for water splitting, but their efficiency lags behind that of inorganic counterparts partly due to the limited charge transport and optical absorption properties. To overcome this limitation, we proposed to employ three-dimensional (3D) fully conjugated (FC) COFs with a topological assembly of cyclooctatetraene derivatives for photocatalytic water splitting. On the basis of first-principles calculations, we demonstrated that these 3D FC-COFs are semiconductors with exceptional charge transport and optical absorption properties. The carrier mobilities are comparable to those of inorganic semiconductors and superior to the record mobility observed in two-dimensional COFs. Additionally, the 3D FC-COFs exhibit broad visible light absorption with direct band gaps and high optical absorption coefficients. Among them, two 3D FC-COFs are identified for overall water splitting, while three others can facilitate the hydrogen evolution half-reaction. This study pioneers the design of 3D FC-COF photocatalysts, potentially advancing their applications in photocatalysis and optoelectronics.
RESUMEN
Two-dimensional (2D) covalent organic frameworks (COFs) with versatile structural and optoelectronic properties that can be tuned with building blocks and topological structures have received widespread attention for photocatalytic water splitting in recent years. However, few of these have been reported for overall water splitting under visible light. Here, we present a data-driven search of 2D COFs capable of visible-light-driven overall water splitting by combining high-throughput first-principles computations and experimental validations. Seven 2D COFs were identified to be capable of overall water splitting from the CoRE COF database, and their photocatalytic activities were further verified and optimized by our preliminary experiments. The production rates of H2 and O2 reached 80 and 32 µmol g-1â¯h-1, respectively, without using sacrificial agents. This work represents an attempt to explore 2D COFs for visible-light-driven overall water splitting with a data-driven approach that could accelerate the discovery and design of COFs toward photocatalytic overall water splitting.