Grafting Hypercrosslinked Polymers on TiO₂ Surface for Anchoring Ultrafine Pd Nanoparticles: Dramatically Enhanced Efficiency and Selectivity toward Photocatalytic Reduction of CO₂ to CH₄

Abstract

Metal deposition with photocatalyst is a promising way to surmount the restriction of fast e−/h+ recombination to improve the photocatalytic performance. However, the improvement remains limited by the existing strategies adopted for depositing metal particles due to the serious aggregation and large unconnected area on photocatalyst surface. Here, a strategy is proposed by directly grafting hypercrosslinked polymers (HCPs) on TiO2 surface to construct Pd‐HCPs‐TiO2 composite with uniform dispersion of ultrafine Pd nanoparticles on HCPs surface. This composite with surface area of 373 m2 g−1 exhibits improved photocatalytic CO2 conversion efficiency to CH4 with an evolution rate of 237.4 µmol g−1 h−1 and selectivity of more than 99.9%. The enhancement can be ascribed to the grafted porous HCPs with high surface area and N heteroatom on TiO2 surface for the stabilization of Pd nanoparticles, favoring the electron transfer and CO2 adsorption for selective CH4 production. This strategy may hold the promise for design and construction of porous organic polymer with semiconductor for efficient photocatalytic conversion.

Photocatalytic CO2 Conversion Using Metal-Containing Coordination Polymers and Networks: Recent Developments in Material Design and Mechanistic Details

“…Structural stability was also given; the production rate was maintained with a value of over 80%, even after five cycles. Pd favored subsequent hydrogenation reduction in CO 2 , enabling methane formation with a high selectivity [ 83 ].…”

Oxygen Vacancy-Induced Construction of CoO/h-TiO2 Z-Scheme Heterostructures for Enhanced Photocatalytic Hydrogen Evolution

“…Photocatalytic water splitting is an available method with high effectiveness to solve energy and environmental problems. Because TiO 2 is environmentally friendly and has stable chemical properties, , it has been widely used in photocatalysis. − However, the large bandgap (3.0–3.2 eV) of TiO 2 limits its absorption and utilization of only about 5% of the solar ultraviolet light . Therefore, regulating the morphological structure, lattice defects, and crystal phase types of TiO 2 is particularly important to improve its light absorption capacity and photocatalytic property. , Two-dimensional TiO 2 nanosheets have the advantages of small size, thin thickness, and large specific surface area, which can accelerate the migration of photogenerated carriers to the surface; meanwhile, it is conducive to improving the photocatalytic activity. , Chen et al prepared black hydrogenated TiO 2 by high-pressure hydrogenation for the first time and successfully extended its light absorption range to the infrared region, setting off the application tide of h-TiO 2 in the field of photocatalysis .…”

3D/2D Heterojunction Fabricated from RuS2 Nanospheres Encapsulated in Polymeric Carbon Nitride Nanosheets for Selective Photocatalytic CO2 Reduction to CO

“…The conversion of CO 2 into high value-added chemicals is one of the most desirable paths for carbon emission reduction because excessive CO 2 emission has destroyed the natural carbon cycle process and exacerbated global warming. − Photocatalytic reduction driven by renewable solar energy is considered as a promising CO 2 conversion technique to tackle energy depletion and environment deterioration problems, − which can effectively conquer the thermodynamic limitations of breaking CO bonds owing to the high dissociation energy (about 750 kJ/mol) . However, for most photocatalysts reported, the low conversion efficiency and poor selectivity remain the unsolved challenging issues in the photocatalytic reduction of CO 2 into CO, CH 3 OH, CH 4 , etc. − Therefore, exploiting a new efficient alternative or structure modification strategy is much desired for photocatalysts.…”