Noble metal free chromophore-catalyst assembly constructed by atomic layer deposition of a stable dye-sensitized photosynthesis cell photocathode for CO₂ reduction

Stable dye-sensitized photoelectrosynthesis cells (DSPECs) relying on non-precious metals for CO₂ reduction to solar fuels represent a promising yet challenging strategy. Herein, a noble-metal-free photocathode (FTO|NiO|P1|TiO₂|CotpyP|TiO₂) is engineered via atomic layer deposition (ALD)-assisted layer-by-layer assembly, integrating a triphenylamine organic dye (P1) and cobalt terpyridine catalyst (CotpyP) within TiO₂-protected NiO films. Under simulated sunlight, the optimized system achieves a CO turnover number of 103 at -0.55 V vs. RHE with a stable photocurrent density of -129.8 µA cm^-2 over 7,200 s, maintaining a syngas H₂/CO ratio of 2.0-a 17-fold lower than CotpyP-free counterparts. ALD-deposited TiO₂ layers suppress catalyst leaching (< 10% loss) while enhancing interfacial charge transfer, yielding an apparent quantum yield of 60% at 450 nm. Control experiments confirm the synergistic roles of P1 (light harvesting) and CotpyP (CO selectivity). This strategy for synthesizing stable non-precious-metal photoelectrode provides a new direction for the development of chromophore-catalyst photocathodes.