Stabilizing Porous-Silicon Photocathodes Via Nickel/Nickel Oxide Co-Catalyst and Benzotriazole Passivation
Rakymbekova A. Magazov Y. Kudryashov V. Ibrayev N. Adilov S. Nuraje N.
December 2025Engineered Science Publisher
ES Materials and Manufacturing
2025#30
Efficient photoelectrochemical water splitting requires stable photoelectrodes that combine strong light harvesting with low-resistance interfaces to facilitate separation of photogenerated charges. Texturing silicon into a 1µm porous (“black Si”) surface layer minimizes front-surface reflection and enhances light trapping. Building on this concept, we fabricate a BTA/NiOx-Ni/pSi photocathode in which a conformal Ni/NiOx layer both protects the substrate and serves as a cocatalyst for the hydrogen evolution reaction. This architecture leverages Ni’s work function (comparable to Pt) and the complementary roles of Ni/NiOx in photocarrier management, thereby accelerating interfacial kinetics. An ultrathin benzotriazole overlayer further inhibits corrosion on Ni, stabilizing the catalyst-silicon contact and suppressing interfacial recombination. Under AM1.5G one-sun illumination, the optimized BTA/NiOx-Ni/pSi delivers a photocurrent density of-0.33 mA cm-2 at-0.30 V vs RHE and retains >90% of its initial current after 1 h. Electrochemical impedance spectroscopy confirms improved interfacial properties, with the charge-transfer resistance decreasing from 1500 Ω (porous Si) to 450 Ω and the series resistance from 200 Ω (flat Si) to 75 Ω. These results demonstrate a synergistic porous-light-trapping + Ni/NiOx cocatalysts + BTA passivation strategy that advances stable, noble-metal-free silicon photocathodes for sustainable H2 production.
Benzotriazole , Black Si, Photoelectrochemical water splitting , Hydrogen generation , Nickel , Nickel oxide , Porous silicon
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Renewable Energy Lab, National Laboratory Astana, Astana, 010000, Kazakhstan
Department of Chemistry, School of Sciences and Humanities, Nazarbayev University, Astana, 010000, Kazakhstan
Institute of Molecular Nanophotonics, Buketov Karaganda University, Karaganda, 100024, Kazakhstan
Department of Chemical and Materials Engineering, Nazarbayev University, Astana, 010000, Kazakhstan
Teqnovate LLC, Astana, 010000, Kazakhstan
Renewable Energy Lab
Department of Chemistry
Institute of Molecular Nanophotonics
Department of Chemical and Materials Engineering
Teqnovate LLC
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