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The oxygen evolution reaction, which involves high overpotential and slow charge-transport kinetics, plays a critical role in determining the efficiency of solar-driven water splitting. The chiral-induced spin selectivity phenomenon has been utilized to reduce by-product production and hinder charge recombination. To fully exploit the spin polarization effect, we herein propose a dual spin-controlled perovskite photoelectrode. The three-dimensional (3D) perovskite serves as a light absorber while the two-dimensional (2D) chiral perovskite functions as a spin polarizer to align the spin states of charge carriers. Compared to other investigated chiral organic cations, R-/S-naphthyl ethylamine enable strong spin-orbital coupling due to strengthened π–π stacking interactions. The resulting naphthyl ethylamine-based chiral 2D/3D perovskite photoelectrodes achieved a high spin polarizability of 75%. Moreover, spin relaxation was prevented by employing a chiral spin-selective L-NiFeOOH catalyst, which enables the secondary spin alignment to promote the generation of triplet oxygen. This dual spin-controlled 2D/3D perovskite photoanode achieves a 13.17% of applied-bias photon-to-current efficiency. Here, after connecting the perovskite photocathode with L-NiFeOOH/S-naphthyl ethylamine 2D/3D photoanode in series, the resulting co-planar water-splitting device exhibited a solar-to-hydrogen efficiency of 12.55%. Enhancing the efficiency of solar-driven water splitting is challenging but highly interesting. Here the authors report a dual spin-controlled 2D/3D perovskite photoelectrode that achieves 12.55% efficiency by utilizing the chiral-induced spin selectivity phenomenon. [ABSTRACT FROM AUTHOR]

Hydrogen production techniques based on solar-water splitting have emerged as carbon-free energy systems. Many researchers have developed highly efficient thin-film photoelectrochemical (PEC) devices made of low-cost and earth-abundant materials. However, solar water splitting systems suffer from short lifetimes due to catalyst instability that is attributed to both chemical dissolution and mechanical stress produced by hydrogen bubbles. A recent study found that the nanoporous hydrogel could prevent the structural degradation of the PEC devices. In this study, we investigate the protection mechanism of the hydrogel-based overlayer by engineering its porous structure using the cryogelation technique. Tests for cryogel overlayers with varied pore structures, such as disconnected micropores, interconnected micropores, and surface macropores, reveal that the hydrogen gas trapped in the cryogel protector reduce shear stress at the catalyst surface by providing bubble nucleation sites. The cryogelated overlayer effectively preserves the uniformly distributed platinum catalyst particles on the device surface for over 200 h. Our finding can help establish semi-permanent photoelectrochemical devices to realize a carbon-free society. Photoelectrodes made of earth-abundant materials can contribute to low-cost and carbon-free hydrogen production, but suffer from a short lifetime. Here the authors report cryogel overlayer to increase the operation time of the device by regulating evolving hydrogen bubble dynamics. [ABSTRACT FROM AUTHOR]

Recently, lead halide perovskites have attracted significant attention as promising absorber materials for photoelectrochemical (PEC) solar water splitting. However, charge‐accumulation‐induced ion migration at the interface causes perovskite degradation and efficiency loss. To suppress the charge accumulation and improve the PEC performance of the perovskite photoanode, a simple interface engineering is proposed by decorating the SnO2/perovskite interface with a mixture of polyethylenimine ethoxylated (PEIE) and chlorobenzenesulfonic acid (CBSA). The mixed CBSA+PEIE treatment effectively passivates the oxygen vacancies in SnO2 and adjusts the band alignment between SnO2 and the perovskite. The synergistic effects of the mixture treatment facilitate an effective carrier extraction at the SnO2/perovskite interface, enhance the PEC performance, and improve the stability of the device. The perovskite photoanode exhibits an impressive applied bias photon‐to‐current efficiency of 12.9% with an outstanding durability for 225 h. Furthermore, an unbiased solar water splitting is achieved using all the perovskite photoelectrodes, resulting in a remarkable unassisted solar‐to‐hydrogen efficiency of 10.9% and a continuous 22 h stable operation. [ABSTRACT FROM AUTHOR]

Oxygen evolution reaction (OER) as a half‐anodic reaction of water splitting hinders the overall reaction efficiency owing to its thermodynamic and kinetic limitations. Iodide oxidation reaction (IOR) with low thermodynamic barrier and rapid reaction kinetics is a promising alternative to the OER. Herein, we present a molybdenum disulfide (MoS2) electrocatalyst for a high‐efficiency and remarkably durable anode enabling IOR. MoS2 nanosheets deposited on a porous carbon paper via atomic layer deposition show an IOR current density of 10 mA cm–2 at an anodic potential of 0.63 V with respect to the reversible hydrogen electrode owing to the porous substrate as well as the intrinsic iodide oxidation capability of MoS2 as confirmed by theoretical calculations. The lower positive potential applied to the MoS2‐based heterostructure during IOR electrocatalysis prevents deterioration of the active sites on MoS2, resulting in exceptional durability of 200 h. Subsequently, we fabricate a two‐electrode system comprising a MoS2 anode for IOR combined with a commercial Pt@C catalyst cathode for hydrogen evolution reaction. Moreover, the photovoltaic–electrochemical hydrogen production device comprising this electrolyzer and a single perovskite photovoltaic cell shows a record‐high current density of 21 mA cm–2 at 1 sun under unbiased conditions. [ABSTRACT FROM AUTHOR]

The lack of highly efficient photoanodes presents a significant challenge to implementing the promising strategy of unbiased solar‐to‐fuel conversion. To achieve high‐performance photoanodes, improving their light harvesting and charge separation/injection capabilities is indispensable. Herein, solution‐processed vertically oriented Sb2S3 nanorod arrays on substrate are obtained via a Au seed layer, resulting in improved optoelectronic properties (due to the light scattering effect) and favorable crystallographic orientation of the 1D nanostructure. Moreover, the (NH4)2WS4 treatment caps the surface of the nanorods with an amorphous WSx layer and passivates the sulfur vacancy of Sb2S3, resulting in boosted charge extraction to the reactants. The resulting photoanode is employed to drive an iodide oxidation reaction (IOR), which is a prominent alternative to sluggish water oxidation reactions, exhibiting a high photocurrent density of 13 mA cm−2 at 0.6 V versus the reversible hydrogen electrode. Subsequently, an unassisted hydrogen generation device is demonstrated by combining an Sb2S3 nanorod array‐based photoanode for IOR and a perovskite‐based photocathode for the hydrogen evolution reaction, achieving an efficient hydrogen production current density of 5.7 mA cm−2 without any external bias. [ABSTRACT FROM AUTHOR]

To realize practical solar hydrogen production, a low‐cost photocathode with high photocurrent density and onset potential should be developed. Herein, an efficient and stable overall photoelectrochemical tandem cell is developed with a Cu3BiS3‐based photocathode. By exploiting the crystallographic similarities between Bi2S3 and Cu3BiS3, a one‐step solution process with two sulfur sources is used to prepare the Bi2S3–Cu3BiS3 blended interlayer. The elongated Bi2S3‐Cu3BiS3 mixed‐phase 1D nanorods atop a planar Cu3BiS3 film enable a high photocurrent density of 7.8 mA cm−2 at 0 V versus the reversible hydrogen electrode, with an onset potential of 0.9 VRHE. The increased performance over the single‐phase Cu3BiS3 thin‐film photocathode is attributed to the enhanced light scattering and charge collection through the unique 1D nanostructure, improved electrical conductivity, and better band alignment with the n‐type CdS layer. A solar‐to‐hydrogen efficiency of 2.33% is achieved under unassisted conditions with a state‐of‐the‐art Mo:BiVO4 photoanode, with excellent stability exceeding 21 h. [ABSTRACT FROM AUTHOR]

Although various electrocatalysts have been developed to ameliorate the shuttle effect and sluggish Li-S conversion kinetics, their electrochemical inertness limits the sufficient performance improvement of lithium-sulfur batteries (LSBs). In this work, an electrochemically active MoO 3 /TiN-based heterostructure (MOTN) is designed as an efficient sulfur host that can improve the overall electrochemical properties of LSBs via prominent lithiation behaviors. By accommodating Li ions into MoO 3 nanoplates, the MOTN host can contribute its own capacity. Furthermore, the Li intercalation process dynamically affects the electronic interaction between MoO 3 and TiN and thus significantly reinforces the built-in electric field, which further improves the comprehensive electrocatalytic abilities of the MOTN host. Because of these merits, the MOTN host-based sulfur cathode delivers an exceptional specific capacity of 2520 mA h g -1 at 0.1 C. Furthermore, the cathode exhibits superior rate capability (564 mA h g -1 at 5 C), excellent cycling stability (capacity fade rate of 0.034% per cycle for 1200 cycles at 2 C), and satisfactory areal capacity (6.6 mA h cm -2 ) under a high sulfur loading of 8.3 mg cm -2 . This study provides a novel strategy to develop electrochemically active heterostructured electrocatalysts and rationally manipulate the built-in electric field for achieving high-performance LSBs., (© 2024 The Author(s). Small published by Wiley‐VCH GmbH.)