Synergistic engineering of Sn-doped β-Fe2O3/Ti3C2Tx photoanodes for efficient photoelectrochemical seawater splitting

The deployment of photoelectrochemical (PEC) water splitting systems in seawater remains a formidable challenge due to the corrosive nature of chloride ions and the instability of most photoanode materials under such conditions. Here, we report a synergistic approach based on Sn-doped β-Fe 2 O 3 photoanodes modified with a conductive Ti 3 C 2 T x MXene interfacial layer. While the Sn doping enhances electronic conductivity and mitigates chloride-induced degradation, the Ti 3 C 2 T x coating plays a pivotal role in accelerating interfacial charge extraction and suppressing surface recombination. The resulting Sn:β-Fe 2 O 3 /Ti 3 C 2 T x photoanode achieves a photocurrent density of 2.81 mA cm −2 at 1.6 V RHE under optimized conditions, representing an 8.2-fold enhancement over pristine β-Fe 2 O 3 , and retains 91.5 % of its activity after 200 h of continuous illumination. This remarkable improvement is attributed to the increased charge carrier density, improved electronic conductivity, and efficient suppression of surface recombination pathways provided by the synergistic effects of Sn doping and Ti 3 C 2 T x interfacial engineering. These findings highlight the effectiveness of 2D MXene integration as a co-catalytic strategy to enable durable and high-performance PEC water splitting in saline environments, offering a scalable route toward solar hydrogen production from abundant seawater resources. • Sn doping and Ti 3 C 2 T x cocatalyst synergistically boost β-Fe 2 O 3 seawater PEC. • Optimized 3 % Sn:β-Fe 2 O 3 /Ti 3 C 2 T x (50 μL): 2.81 mA cm −2 at 1.6 V RHE . • Stable operation: retaining 91.5 % of the activity after 200 h. • Rct reduced from 1791 to 262.1 Ω; donor density increases 6.9 times. • Bandgap narrows 1.97 to 1.79 eV, enhancing absorption and charge separation.