Low-Temperature Atomic Layer Deposition of Cobalt Oxide as an Effective Catalyst for Photoelectrochemical Water-Splitting Devices

Abstract

We have developed a low-temperature atomic layer deposition (ALD) process for depositing crystalline and phase pure spinel cobalt oxide (Co3O4) films at 120 °C using [Co(tBu2 DAD)2] and ozone as co-reagent. X-ray diffraction, UV-Vis spectroscopy, atomic force microscopy, field emission scanning electron microscopy, X-ray photoelectron spectroscopy and time-of-flight elastic recoil detection analysis were performed to characterize the structure and properties of the films. The as-deposited Co3O4 films are crystalline with low amount of impurities (<2 % C and <5 % H) despite low deposition temperatures. Deposition of Co3O4 onto thin TiO2 photoanodes (100 nm) for water oxidation resulted in 30 % improvement of photocurrent (after 10 ALD cycles yielding small Co3O4 particles) as compared to pristine TiO2 films), and exhibited no detrimental effects on photocurrent response up to 300 deposition cycles (approximately 35 nm thick films), demonstrating the applicability of the developed ALD process for deposition of effective catalyst particles and layers in photoelectrochemical water-splitting devices.

Johann-type laboratory-scale x-ray absorption spectrometer with versatile detection modes

“…In addition to the Co foil, we measured 100 nm thick CoO and Co 3 O 4 films [38] grown on a silicon substrate using atomic layer deposition [39,40] The thin film spectra together with the powder references measured in transmission are presented in Fig. 11.…”

Isostructural NiII Metal–Organic Frameworks (MOFs) for Efficient Electrocatalysis of Oxygen Evolution Reaction and for Gas Sorption Properties

“…Currently,r uthenium oxide (RuO 2 )a nd iridium oxide (IrO n )a re the benchmark catalysts for OER. [12,13] Cobalt-phosphates in neutral media and Co-containingc halcogenidesa nd perovskites in alkaline media were also found to be efficient OER electrocatalysts. Consequently,t here is an urgentn eed to develop low cost, highly durable and novel crystalline solid materials exhibiting efficient catalytic activity,f rom earth-abundant elements as an alternative to RuO 2 and IrO 2 at ambient conditions.…”

“…[36,37] In particular,N i-containing MOFs are of great interest for water oxidation due to their water stability,a ppreciable redox properties of Ni and the strong oxidizing powero fi ts valences tates. 19.513 (13) 19.576(4) a (8)90 90 b (8)93.375 (12) 92.852 (14) [40][41][42] Recently,h etero-NiFe bimetallic MOF was shown as ar obust electrode materialf or electrochemical OER.…”

“…[8][9][10][11] Amongt he TMOs, cobalt-based spinel oxides have been shown as outstanding OER electrocatalysts. [12,13] Cobalt-phosphates in neutral media and Co-containingc halcogenidesa nd perovskites in alkaline media were also found to be efficient OER electrocatalysts. [14][15][16][17] MOFs have attracted immense attention during the past few years fort heir fascinating, diverse structural architectures,a nd more importantly for their novel intrinsic and extrinsic properties.…”

A combinatorial approach to enhance barrier properties of thin films on polymers: Seeding and capping of PECVD thin films by PEALD

“…With its self‐limiting growth by sequential half‐cycles, ALD and PEALD processes are capable of producing pin‐hole free and highly conformal thin films. While thermal ALD can be used to deposit many materials already at low temperatures, the adaption of PEALD enables depositions even at room temperature by using highly reactive plasma species which can provide a more efficient deposition in terms of shorter cycle times. The low substrate temperatures are an appealing benefit of PEALD especially within the context of coating sensitive polymers.…”