Photoelectrochemical (PEC) water splitting offers a promising route for harnessing solar energy to produce clean hydrogen fuel sustainably. A major hurdle has been boosting the performance of photoanode materials within acidic electrolytes—a critical aspect for advancing PEC technology. In response to this challenge, we report a method to augment the efficacy of hematite photoanodes under acidic conditions by anchoring IrO_x nanoparticles, replete with hydroxyl groups, onto their surface. A remarkable and steady photocurrent density of 1.71 mA cm⁻² at 1.23 V versus RHE was achieved, marking a significant leap in PEC efficiency of hematite in acidic media. The introduction of the IrO_x layer notably expanded the electrochemically active surface area for more active sites, fostering improved charge separation and transfer. It also served as an effective hole capture layer, drawing photogenerated holes from hematite to facilitate swift migration to the active sites for the water oxidation process. This advancement has the potential to fully harness the capabilities of hematite photoanodes in acidic environments, thereby smoothing the path toward more effective and sustainable hydrogen production through PEC water splitting.

To exploit high-performance and stable sensing materials with a room working temperature is pivotal for portable and mobile sensor devices. However, the common sensors based on metal oxide semiconductors usually need a higher working temperature (usually above 300 °C) to achieve a good response toward gas detection. Currently, metal halide perovskites have begun to rise as a promising candidate for gas monitoring at room temperature but suffer phase instability. Herein, we construct 1D/3D PyPbI₃/FA_0.83Cs_0.17PbI₃ (denoted by PyPbI₃/FACs) bilayer perovskite by post-processing spin-coating Pyrrolidinium hydroiodide (PyI) salt on top of 3D FACs film. Benefitting from the 1D PyPbI₃ coating layer, the phase stability of 1D/3D PyPbI₃/FACs significantly improves. Simultaneously, the gas sensor based on the 1D/3D PyPbI₃/FACs bilayer perovskite presents a superior selectivity and sensitivity toward NO₂ detection at room temperature, with a low detection limit of 220 ppb. Exposed to a 50 ± 3% relative humidity (RH) level environment for a consecutive six days, the 1D/3D PyPbI₃/FACs perovskite-based sensor toward 10 ppm NO₂ can still maintain a rapid response with a slight attenuation. Gas sensors based on hybrid 1D/3D-structured perovskite in this work may provide a new pathway for highly sensitive and stable gas sensors in room working temperature, accelerating its practical application and portable device.

The exploration of high-performance and low-cost electrocatalysts towards the oxygen evolution reaction (OER) is essential for large-scale water/seawater splitting. Herein, we develop a strategy involving the in situ generation of a template and pore-former to encapsulate a Ni₅P₄/Ni₂P heterojunction and dispersive FeNi alloy hybrid particles into a three-dimensional hierarchical porous graphitic carbon framework (labeled as Ni₅P₄/Ni₂P–FeNi@C) via a room-temperature solid-state grinding and sodium-carbonate-assisted pyrolysis method. The synergistic effect of the components and the architecture provides a large surface area with a sufficient number of active sites and a hierarchical porous pathway for efficient electron transfer and mass diffusion. Furthermore, a graphitic carbon coating layer restrains the corrosion of alloy particles to boost the long-term durability of the catalyst. Consequently, the Ni₅P₄/Ni₂P–FeNi@C catalyst exhibits extraordinary OER activity with a low overpotential of 242 mV (10 mA cm⁻²), outperforming the commercial RuO₂ catalyst in 1 M KOH. Meanwhile, a scale-up of the Ni₅P₄/Ni₂P–FeNi@C catalyst created by a ball-milling method displays a similar level of activity to the above grinding method. In 1 M KOH + seawater electrolyte, Ni₅P₄/Ni₂P–FeNi@C also displays excellent stability; it can continuously operate for 160 h with a negligible potential increase of 2 mV. This work may provide a new avenue for facile mass production of an efficient electrocatalyst for water/seawater splitting and diverse other applications.