Boosted charge transport through Au-modified NiFe layered double hydroxide on silicon for efficient photoelectrochemical water oxidation

• Published in: Journal of materials chemistry. A, Materials for energy and sustainability Materials for energy and sustainability, 2023-08, Vol.11 (33), p.1753-17513
• Main Authors: Choi, Sungkyun, Lee, Sol A, Yang, Jin Wook, Sohn, Woonbae, Kim, Jaehyun, Cheon, Woo Seok, Park, Jaemin, Cho, Jin Hyuk, Lee, Chung Won, Jun, Sang Eon, Park, Sung Hyuk, Moon, Jooho, Kim, Soo Young, Jang, Ho Won
• Format: Article
• Language: English
• Subjects: Catalysts; Charge transport; Density; Electrolytes; Electronic structure; Gold; Hydrogen-based energy; Hydroxides; Intermetallic compounds; Iron compounds; Kinetics; Metal concentrations; Metals; Nickel compounds; Noble metals; Oxidation; Oxygen evolution reactions; Photoelectric effect; Photoelectric emission; Recombination; Silicon; Solar energy; Synergistic effect; Transition metals; Water splitting
• ISSN: 2050-7488; 2050-7496
• DOI: 10.1039/d3ta03075j

Designing an appropriate oxygen evolution reaction (OER) catalyst for photoelectrochemical (PEC) water splitting is an urgent issue for providing high-efficiency solar to hydrogen energy production. Transition metals have been central to OER catalyst research due to their plentifulness and specific electronic structure, but overcoming their water oxidation limits, including high overpotential and sluggish kinetics, remains challenging. The effective usage of noble metals for the OER, such as an intentional introduction of low-concentration noble metals into earth-abundant materials, can complement the limited reserve of noble metals and largely enhance the entire efficiency of solar water oxidation. Herein, we developed an OER photoelectrode of Au-incorporated NiFe layered double hydroxide (LDH) placed on a strong light absorber n-type silicon (Au-NiFe LDH/n-Si). With a minimal Au content of 2.7% in the catalyst structure, synergistic effects between noble metal Au and transition metal-based NiFe LDH notably accelerated the OER kinetics while stabilizing the Si-based photoanode structure in corrosive alkaline electrolyte. Optimally fabricated Au-NiFe LDH through a facile two-step electrodeposition process on n-Si exhibited a high saturated photocurrent density of ∼37 mA cm −2 , and the saturated photocurrent density could be reached at an early underpotential point of 1.2 V vs. RHE. Moreover, it operated for ∼50 hours in pH 11.5 electrolyte, showing 5 times higher stability than NiFe LDH/n-Si under the same alkaline conditions. One step further, a 1/48 decrease in recombination kinetics could be achieved through doping Au atoms into NiFe LDH, revealing the efficacious defect site passivation effect with the minimum amount of noble metal usage. Atomically doped Au in NiFe-LDH effectively passivates defect sites, substantially enhancing overall PEC water oxidation properties.