Cobalt‐Sputtered Anodic Aluminum Oxide Membrane for Efficient Photothermal CO₂ Hydrogenation

Abstract

The rational design of nanoarray‐structured catalysts is an accessible way to increase light absorption ability and boost photothermal CO2 conversion efficiency. However, practical application of current nanoarrays is hindered by complex synthesis procedures, high costs, and low catalyst yields. Herein, we report a simple, robust method to prepare efficient photothermal catalyst by sputtering Co nanoparticles on commercial anodic aluminum oxide (AAO) membrane. The detailed study shows that gas diffusion and catalytic activity can be affected by AAO structures, such as channel size and shape. The optimized Co@dpAAO catalyst reached a record Co‐based photothermal CO2 conversion rate of 1666 mmol ⋅ gCo−1 ⋅ h−1. This study not only provides a facile way to synthesize efficient catalysts, but also promotes the understanding of constructing nanoarray‐based photothermal catalysts.

Nanoporous Anodic Alumina Photonic Crystals for Sunlight Harvesting Applications: A Perspective

“…Lou et al achieved a high photothermal carbon dioxide (CO 2 ) hydrogenation rate by sputter depositing cobalt (Co) NPs onto NAA structures. [ 121 ] The CO 2 conversion rate of the system reached 1666 mmol g Co −1 h −1 , which is the highest reported for Co‐based systems. Dark amorphous TiO x nanotube arrays were investigated by Liu et al for solar thermal conversion.…”

“…Owing to the high aspect ratio of the pores in NAA, deposition of functional coatings via sputtering is constrained to the top surface and to a limited penetration distance inside the inner surface of the pores (Figure 7e). The utilization of sputter deposition onto NAA structures has mainly three purposes: 1) to provide a conductive layer on either the backside or top surface of NAA membranes (metals, especially gold, are typically deposited for this purpose); 2) to provide or further improve the material's properties such as catalytic or plasmonic activity; [121][122][123][124] 3) to modify the intrinsic optical properties of NAA-based PCs [38,79,[123][124][125][126][127] . In the latter configuration, both the sputtered metal coating and the NAA-PC can be precisely engineered to attain specific interactions with incoming photons.…”

Rationally designed nanoarray catalysts for boosted photothermal CO2 hydrogenation

“…Typically, the metals of array-based catalysts are loaded by magnetron sputtering. 26,27 Although tuning the sputtering deposition conditions can reduce the particle size, the straight up-and-down structure of nanowire and nanorod arrays will inevitably cause a wider distribution of metal particles. Agglomeration and overgrowth of metal nanoparticles can be found at the top of array structures, and these phenomena will also result in poor dispersity and low atomic utilization of decorated metals.…”

“…Agglomeration and overgrowth of metal nanoparticles can be found at the top of array structures, and these phenomena will also result in poor dispersity and low atomic utilization of decorated metals. 27,28 In addition, nanoarray structures and metal nanoparticles absorb light and act as active sites while the substrate beneath the arrays is almost useless for light absorption and catalysis but accelerates heat dissipation and weakens the catalytic performance. Therefore, it is still a big challenge to optimize nanoarray-based photothermal catalysts and obtain superior photothermal catalytic performance with enhanced dispersion of active sites and good light-to-heat conversion properties.…”

Incorporation of Ions into Nanostructured Anodic Oxides—Mechanism and Functionalities

“…An impressive amount of research on anodic alumina provides progress in nanofabrication [19] of materials with emerging applications-like biomimetic materials [20], CO 2 conversion [21], energy storage [22], or superconductive materials [23]-and stimulates research on the anodization of other metals. The most significant applications of nanostructured oxides formed by the anodization of popular metals are presented in Figure 2.…”