RESUMEN
The unsatisfactory adsorption and activation of CO2 suppress electrochemical reduction over a wide potential window. Herein, the built-in electric field (BIEF) at the CeO2/In2O3 n-n heterostructure realizes the C1 (CO and HCOO-) selectivity over 90.0% in a broad range of potentials from -0.7 to -1.1 V with a maximum value of 98.7 ± 0.3% at -0.8 V. In addition, the C1 current density (-1.1 V) of the CeO2/In2O3 heterostructure with a BIEF is about 2.0- and 3.2-fold that of In2O3 and a physically mixed sample, respectively. The experimental and theoretical calculation results indicate that the introduction of CeO2 triggered the charge redistribution and formed the BIEF at the interfaces, which enhanced the interfacial adsorption and activation of CO2 at low overpotentials. Furthermore, the promoting effect was also extended to CeO2/In2S3. This work gives a deep understanding of BIEF engineering for highly efficient CO2 electroreduction over a wide potential window.
RESUMEN
The electrochemical reduction of CO2 (CO2 RR) is a promising approach to maintain a carbon cycle balance and produce value-added chemicals. However, CO2 RR technology is far from mature, since the conventional CO2 RR electrocatalysts suffer from low activity (leading to currents <10â mA cm-2 in an H-cell), stability (<120â h), and selectivity. Hence, they cannot meet the requirements for commercial applications (>200â mA cm-2 , >8000â h, >90 % selectivity). Significant improvements are possible by taking inspiration from nature, considering biological organisms that efficiently catalyze the CO2 to various products. In this minireview, we present recent examples of enzyme-inspired and enzyme-mimicking CO2 RR electrocatalysts enabling the production of C1 products with high faradaic efficiency (FE). At present, these designs do not typically follow a methodical approach, but rather focus on isolated features of biological systems. To achieve disruptive change, we advocate a systematic design methodology that leverages fundamental mechanisms associated with desired properties in nature and adapts them to the context of engineering applications.
RESUMEN
The conversion of CO2 into high-value added chemicals driven by solar energy is an effective way to solve environmental problems, which is, however, largely restricted by the competition reaction of the hydrogen evolution reaction (HER) and easy electron-hole recombination, etc. Herein, VO4 -supported ultrathin NiMgV-layered double hydroxide (V/NiMgV-LDH) nanosheets are successfully fabricated, and the extended X-ray absorption fine structure (EXAFS) and density function theory (DFT) calculations reveal that VO4 species are located on the top of V atoms in the NiMgV-LDH laminate. The V/NiMgV-LDH is proved to be highly efficient for the photocatalytic CO2 reduction reaction (CO2 PR) with high selectivity of 99% for C1 products and nearly no HER (<1%) takes place under visible light. Contrast experiments using NiMgV-LDH as the catalyst for CO2 PR show a CO selectivity of 71.40% and a H2 selectivity of 28.11%. Such excellent performance of V/NiMgV-LDH can be attributed to the following reasons: 1) the V/NiMgV-LDH modulates the band structure and promotes the separation of electrons and holes; 2) strong bonding between V/NiMgV-LDH and CO* and H* facilitates the hydrogenation to form CH4 and inhibits the formation of by-product H2 at the same time.
RESUMEN
Electrocatalytic CO2 reduction reaction (CRR) is one of the most promising strategies to convert greenhouse gases to energy sources. Herein, the CRR was applied towards making C1 products (CO, HCOOH, CH3 OH, and CH4 ) on g-C3 N4 frameworks with single Ni, Co, and Fe introduction; this process was investigated by density functional theory. The structures of the electrocatalysts, CO2 adsorption configurations, and CO2 reduction mechanisms were systematically studied. Results showed that the single Ni, Co, and Fe located from the corner of the g-C3 N4 cavity to the center. Analyses of the adsorption configurations and electronic structures suggested that CO2 could be chemically adsorbed on Co-C3 N4 and Fe-C3 N4 , but physically adsorbed on Ni-C3 N4 . The H2 evolution reaction (HER), as a suppression of CRR, was investigated, and results showed that Ni-C3 N4 , Co-C3 N4 , and Fe-C3 N4 exhibited more CRR selectivity than HER. CRR proceeded via COOH and OCHO as initial protonation intermediates on Ni-C3 N4 and Co/Fe-C3 N4 , respectively, which resulted in different C1 products along quite different reaction pathways. Compared with Ni-C3 N4 and Fe-C3 N4 , Co-C3 N4 had more favorable CRR activity and selectivity for CH3 OH production with unique rate-limiting steps and lower limiting potential.
RESUMEN
Electrochemical reduction of CO2 could mitigate environmental problems originating from CO2 emission. Although grain boundaries (GBs) have been tailored to tune binding energies of reaction intermediates and consequently accelerate the CO2 reduction reaction (CO2 RR), it is challenging to exclusively clarify the correlation between GBs and enhanced reactivity in nanostructured materials with small dimension (<10â nm). Now, sub-2â nm SnO2 quantum wires (QWs) composed of individual quantum dots (QDs) and numerous GBs on the surface were synthesized and examined for CO2 RR toward HCOOH formation. In contrast to SnO2 nanoparticles (NPs) with a larger electrochemically active surface area (ECSA), the ultrathin SnO2 QWs with exposed GBs show enhanced current density (j), an improved Faradaic efficiency (FE) of over 80 % for HCOOH and ca. 90 % for C1 products as well as energy efficiency (EE) of over 50 % in a wide potential window; maximum values of FE (87.3 %) and EE (52.7 %) are achieved.