Photocatalytic CO₂ Reduction to CO over Ni Single Atoms Supported on Defect‐Rich Zirconia

Abstract

Photocatalytic CO 2 conversion to CO is currently attracting a lot of attention as an environmentally benign strategy for curbing anthropogenic CO 2 emissions while delivering commodity chemicals. [1] An ideal CO 2 reduction photocatalyst would have a low energy barrier pathway for CO 2 reduction and be highly selective in terms of the product generated. To date, photocatalytic CO 2 reduction remains inefficient and the rates low, which is explained by the chemical stability of CO 2 molecule and the competing water splitting reaction which lowers product selectivity. [2] Considerable research effort is currently being directed toward improving photocatalytic CO 2 reduction kinetics and also tailoring the product distribution of the reaction. However, the simultaneous enhancement of CO 2 photoreduction activity and product selectivity is very challenging. [3] Owing to the maximal active metal utilization, accessibility of active sites and unique catalytic properties, metal singleatom catalysts (SACs) hold great potential in high performance photocatalyst fabrication. [4,5] Immobilization of Co, Fe, Cu, Mn, or Re atoms in zeolites, MOFs, COFs, and lamellar materials (g-C 3 N 4 , graphdiyne) has resulted in a number of catalyst/ photocatalyst systems with highly efficiency/selectivity for photocatalytic CO 2 reduction. [6] However, due to the fact that these single metal atoms are often coordinated by N/C matrix (M-C/N unit), extensive sacrificial agents are often required to achieve stability. [6a,6b] Further, a number of the supports used to date in SAC fabrication such as zeolites, MOFs, and COFs are poor light-absorbers and/or electron-conductors, necessitating the use of photosensitizers as electron donors. [6d] These bottlenecks impair the application of SACs in photocatalytic CO 2 reduction, forcing a rethink in the design and materials used in SAC construction. Recently, a photocatalyst system comprising Co SACs supported by Bi 3 O 4 Br was reported, [7] in which the Co atoms occupied oxygen vacancy sites in Bi 3 O 4 Br. The photocatalyst system offers efficient CO 2 to CO conversion without the need for any sacrificial agents/photosensitizers, representing a major breakthrough in CO 2 reduction reaction (CRR) photocatalyst development. Our previous work has demonstrated that Ni SACs were more active than Co SACs for CO 2 reduction to CO, [8] suggesting that further improvements in photocatalytic performance should be possible by substituting Co for Ni.

Simultaneous Manipulation of Bulk Excitons and Surface Defects for Ultrastable and Highly Selective CO2 Photoreduction

“…The gas products were analyzed using a gas chromatograph‐mass spectrometer (ThermoFisher Trace 1300, USA) equipped with a column for to detect the products of 13 CO (HP‐MOLESIEVE, 30 m × 0.32 mm × 25 µm, Agilent Technologies, USA). [ 51,52 ]…”

Plasmon‐Enhanced Charge Separation and Surface Reactions Based on Ag‐Loaded Transition‐Metal Hydroxide for Photoelectrochemical Water Oxidation

“…Photoelectrochemical (PEC) water splitting has been regarded as a promising way for conversion of solar power to chemical energy. [1][2][3][4][5][6] However, low PEC efficiency mainly resulted from fast surface charge recombination and sluggish oxygen evolution reaction (OER), [7,8] still extremely hampers their applications in PEC and photocatalytic systems.…”

Revealing the Sudden Alternation in Pt@h‐BN Nanoreactors for Nearly 100% CO2‐to‐CH4 Photoreduction

“…For the development of efficient photocatalysts, scientists have done a lot of meaningful work. [ 12–14 ] Jiang et al. [ 15 ] reported that by accurately anchoring TiO 2 in two different molecular compartments of MIL‐101, a quantum efficiency of up to 11.3% was achieved, proving that the precise positioning of TiO 2 in the metal‐organic framework (MOF) system can effectively improve the material performance.…”

“…For the development of efficient photocatalysts, scientists have done a lot of meaningful work. [12][13][14] Jiang et al [15] reported that by accurately anchoring TiO 2 in two different molecular compartments of MIL-101, a quantum efficiency of up to 11.3% was achieved, proving that the precise positioning of TiO 2 in the metal-organic framework (MOF) system can effectively improve the material performance. Li et al [16] reported that through a top-down direct metal atomization method to prepare single atoms and the use of CO species to adjust the coordination environment, a high turnover number of 1493.5 could be achieved in CO 2 photoreduction process.…”