Dynamic Piezoelectric Charge Engineering of Dual Single-Atom COF/g-C3N4 S-Scheme Heterostructures for Efficient Artificial Photosynthesis
Year: 2026
Type: preprint
Abstract: Artificial photosynthesis offers a sustainable route for converting solar energy into chemical fuels while simultaneously addressing the challenges of anthropogenic CO2 emissions and global energy demand. Nevertheless, the practical implementation of photocatalytic CO2 reduction and hydrogen evolution is hindered by limited visible-light absorption, rapid recombination of photogenerated charge carriers, and sluggish surface reaction kinetics. In this work, a dual single-atom Fe–Co catalyst anchored on a covalent organic framework (COF)/graphitic carbon nitride (g-C3N4) S-scheme heterostructure was successfully developed through a rational dynamic piezoelectric charge engineering strategy. The intimate coupling between COF and g-C3N4 established an efficient S-scheme heterojunction, while atomically dispersed Fe–N4 and Co–N4 active sites provided abundant catalytic centers for CO2 activation and proton reduction. Under simultaneous simulated AM 1.5G solar irradiation and ultrasonic mechanical stimulation, dynamic piezoelectric polarization generated an additional internal electric field that reinforced interfacial charge separation and promoted directional carrier migration toward the isolated Fe–Co active sites. Comprehensive structural characterization, including XRD, XPS, aberration-corrected HAADF-STEM, XANES, and EXAFS, confirmed the successful formation of a highly crystalline heterostructure with uniformly dispersed Fe and Co single atoms and the absence of metal aggregation. The optimized Fe–Co SAC/COF/g-C3N4 photocatalyst achieved a CO evolution rate of 756 μmol g-1 h-1 and a H2 evolution rate of 3145 μmol g-1 h-1, representing approximately 13-fold and 11-fold enhancements, respectively, over pristine g-C3N4. The catalyst further exhibited a maximum apparent quantum efficiency of 16.8% at 420 nm, a solar-to-chemical conversion efficiency of 2.6%, and retained more than 94% of its initial photocatalytic activity after ten consecutive reaction cycles. Density functional theory calculations revealed pronounced interfacial charge redistribution, enhanced electronic states near the Fermi level, stronger CO2 adsorption (−0.86 eV), and substantially reduced Gibbs free-energy barriers for *COOH formation (0.36 eV) and hydrogen adsorption (0.18 eV), confirming accelerated multielectron transfer kinetics. The synergistic integration of dynamic piezoelectric polarization, S-scheme charge transfer, and dual single-atom catalysis provides an effective strategy for maximizing solar-to-chemical energy conversion and offers a promising platform for the design of next-generation photocatalysts for efficient artificial photosynthesis and sustainable solar fuel production.
Source: ChemRxiv
Language: English
Field: Energy
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7167574841