Accelerated pyro-catalytic hydrogen production enabled by plasmonic local heating of Au on pyroelectric BaTiO3 nanoparticles

Dynamic regulation of ferroelectric polarization using external stimuli for efficient water splitting and beyond

Establishing and regulating the ferroelectric polarization in ferroelectric nano-scale catalysts has been recognized as an emerging strategy to advance water splitting reactions, with the merits of improved surface charge density, high charge transfer rate, increased electronic conductivity, the creation of real active sites, and optimizing the chemisorption energy. As a result, engineering and tailoring the ferroelectric polarization induced internal electric field provides significant opportunities to improve the surface and electronic characteristics of catalysts, thereby enhancing the water splitting reaction kinetics. In this review, an interdisciplinary and comprehensive summary of recent advancements in the construction, characterization, engineering and regulation of the polarization in ferroelectric-based catalysts for water splitting is provided, by exploiting a variety of external stimuli. This review begins with a detailed overview of the classification, benefits, and identification methodologies of the ferroelectric polarization induced internal electric field; this offers significant insights for an in-depth analysis of ferroelectric-based catalysts. Subsequently, we explore the underlying structure-activity relationships for regulating the ferroelectric polarization using a range of external stimuli which include mechanical, magnetic, and thermal fields to achieve efficient water splitting, along with a combination of two or more fields. The review then highlights emerging strategies for multi-scale design and theoretical prediction of the relevant factors to develop highly promising ferroelectric catalysts for efficient water splitting. Finally, we present the challenges and perspectives on the potential research avenues in this fascinating and new field. This review therefore delivers an in-depth examination of the strategies to engineer the ferroelectric polarization for the next-generation of water electrolysis devices, systems and beyond.

Swift Droplet Manipulation on BTO/Polyimide Slippery Surfaces

Droplet manipulation on functional surfaces is an urgent problem to be solved. Fast and precise droplet manipulation plays an important role in many applications, such as microreactors and microfluidics. Although numerous techniques have been developed to manipulate droplets by injecting external stimuli, it remains a challenge to achieve high-precision, high-sensitivity, and fast droplet manipulation on smart, slippery response surfaces. Here, we report an intelligent slippery photopyroelectric response near-infrared-induced MXene-barium titanate/polyimide (SFMBPI) membrane. By using local near-infrared radiation (NIR), we can precisely control the droplet transport on the SFMBPI membrane, and SFMBPI uses electrospinning technology to better lock the dimethylsilicone oil, reducing the loss during the control process. Moreover, due to the presence of the pyroelectric layer, double external stimuli can be achieved. The thermal stimulation of the photothermal layer and the charge action of the pyroelectric layer make the manipulation of droplets on the SFMBPI surface more efficient and faster. Moreover, the experiment of negative gravity transport at an inclination angle of 6° demonstrates that the existence of the pyroelectric layer results in a greater driving force on the droplets, which can be more widely used. In addition, by inducing the direction of the NIR, programmable droplet transport and droplet merging can be achieved. Also, the SFMBPI membrane can be used for underwater bubble manipulation. This precise manipulation of droplets on the surface of SFMBPI membranes can be widely used in other fields, such as microfluidics.

Ferroelectric, flexoelectric and photothermal coupling in PVDF-based composites for flexible photoelectric sensors

A ferroelectric polyvinylidene fluoride (PVDF) film with excellent flexibility possesses great potential for photodetection and wearable devices. However, the relatively weak photo-absorption and the consequent small photocurrent limit its photofunctional properties. Herein, we embedded a strongly visible-light active material system, 0.5Ba(Zr0.08Ti0.8Mn0.12)O3-0.5(Ba0.7Ca0.3)TiO3 (BZTM-BCT) loaded with Ag and Au nanoparticles, into a PVDF film, which demonstrates a significantly higher photovoltaic response in the whole visible light range with a β-phase content of over 90%. In a state of "bending + poling", the PVDF/BZTM-BCT:Au film presents an optimal response for photoelectric properties by exhibiting a photocurrent that is 57 times higher than that of a pure PVDF film when illuminated with 405 nm LED light at 100 mW cm-2. Photoexcitation and thermal excitation jointly contribute to the generation of free carriers, while the flexoelectric and ferroelectric coupling electric field provides a greater driving force for carrier separation and transport. More interestingly, composite film-based photoelectric sensors can simultaneously respond to light and the movement and deformation of contacted things, indicating its potential in versatile applications. Overall, this work puts forward a new route for designing new flexible multifunctional photoelectric devices.

Rapid fabrication of gold microsphere arrays with stable deep-pressing anisotropic conductivity for advanced packaging

Smooth metal microspheres with uniform sizes are ideal for constructing particle-arrayed anisotropic conductive films (ACF), but synthesis is hindered by challenges in controlling anisotropic metal growth. Here, we present a positioned transient-emulsion self-assembly and laser-irradiation strategy to fabricate pure gold microsphere arrays with smooth surfaces and uniform sizes. The fabrication involves assembling gold nanoparticles into uniform colloidosomes within a pre-designed microhole array, followed by rapid transformation into well-defined microspheres through laser heating. The gold nanoparticles melt and merge in a layer-by-layer manner due to the finite skin depth of the laser, leading to a localized photothermal effect. This strategy circumvents anisotropic growth, enables tunable control of microsphere size and positioning, and is compatible with conventional lithography. Importantly, these pure gold microspheres exhibit stable conductivity under deep compression, offering promising applications in soldering micro-sized chips onto integrated circuits.

Photocatalytic overall water splitting endowed by modulation of internal and external energy fields

The pursuit of sustainable and clean energy sources has driven extensive research into the generation and use of novel energy vectors. The photocatalytic overall water splitting (POWS) reaction has been identified as a promising approach for harnessing solar energy to produce hydrogen to be used as a clean energy carrier. Materials chemistry and associated photocatalyst design are key to the further improvement of the efficiency of the POWS reaction through the optimization of charge carrier separation, migration and interfacial reaction kinetics. This review examines the latest progress in POWS, ranging from key catalyst materials to modification strategies and reaction design. Critical analysis focuses on carrier separation and promotion from the perspective of internal and external energy fields, aiming to trace the driving force behind the POWS process and explore the potential for industrial development of this technology. This review concludes by presenting perspectives on the emerging opportunities for this technology, and the challenges to be overcome by future studies.

A singular plasmonic-thermoelectric hollow nanostructure inducing apoptosis and cuproptosis for catalytic cancer therapy

Thermoelectric technology has recently emerged as a distinct therapeutic modality. However, its therapeutic effectiveness is significantly limited by the restricted temperature gradient within living organisms. In this study, we introduce a high-performance plasmonic-thermoelectric catalytic therapy utilizing urchin-like Cu2-xSe hollow nanospheres (HNSs) with a cascade of plasmonic photothermal and thermoelectric conversion processes. Under irradiation by a 1064 nm laser, the plasmonic absorption of Cu2-xSe HNSs, featuring rich copper vacancies (VCu), leads to a rapid localized temperature gradient due to their exceptionally high photothermal conversion efficiency (67.0%). This temperature gradient activates thermoelectric catalysis, generating toxic reactive oxygen species (ROS) targeted at cancer cells. Density functional theory calculations reveal that this vacancy-enhanced thermoelectric catalytic effect arises from a much more carrier concentration and higher electrical conductivity. Furthermore, the exceptional photothermal performance of Cu2-xSe HNSs enhances their peroxidase-like and catalase-like activities, resulting in increased ROS production and apoptosis induction in cancer cells. Here we show that the accumulation of copper ions within cancer cells triggers cuproptosis through toxic mitochondrial protein aggregation, creating a synergistic therapeutic effect. Tumor-bearing female BALB/c mice are used to evaluate the high anti-cancer efficiency. This innovative approach represents the promising instance of plasmonic-thermoelectric catalytic therapy, employing dual pathways (membrane potential reduction and thioctylated protein aggregation) of mitochondrial dysfunction, all achieved within a singular nanostructure. These findings hold significant promise for inspiring the development of energy-converting nanomedicines.

Symmetry-breaking-induced off-resonance second-harmonic generation enhancement in asymmetric plasmonic nanoparticle dimers

The linear and nonlinear optical properties of metallic nanoparticles have attracted considerable experimental and theoretical research interest. To date, most researchers have focused primarily on exploiting their plasmon excitation enhanced near-field and far-field responses and related applications in sensing, imaging, energy harvesting, conversion, and storage. Among numerous plasmonic structures, nanoparticle dimers, being a structurally simple and easy-to-prepare system, hold significant importance in the field of nanoplasmonics. In highly symmetric plasmonic nanostructures, although the odd-order optical nonlinearity of the near-surface region will be improved because of the enhanced near-fields, even-order nonlinear processes such as second-harmonic generation (SHG) will still be quenched and thus optically forbidden. Under this premise, it is imperative to introduce structural symmetry breaking to realize plasmon-enhanced even-order optical nonlinearity. Here, we fabricate a series of nanoparticle dimers each composed of two gold nanospheres with different diameters and subsequently investigate their structural asymmetry dependent linear and nonlinear optical properties. We find that the SHG intensities of gold nanosphere dimers are significantly enhanced by structural asymmetry under off-resonance excitation while the plasmonic near-field enhancement mainly affects SHG under on-resonance excitation. Our results reveal that symmetry breaking will play an indispensable role when designing novel coupled plasmonic nanostructures with enhanced nonlinear optical properties.

Pulsed laser induced plasma and thermal effects on molybdenum carbide for dry reforming of methane

Dry reforming of methane (DRM) is a highly endothermic process, with its development hindered by the harsh thermocatalytic conditions required. We propose an innovative DRM approach utilizing a 16 W pulsed laser in combination with a cost-effective Mo2C catalyst, enabling DRM under milder conditions. The pulsed laser serves a dual function by inducing localized high temperatures and generating *CH plasma on the Mo2C surface. This activates CH4 and CO2, significantly accelerating the DRM reaction. Notably, the laser directly generates *CH plasma from CH4 through thermionic emission and cascade ionization, bypassing the traditional step-by-step dehydrogenation process and eliminating the rate-limiting step of methane cracking. This method maintains a carbon-oxygen balanced environment, thus preventing the deactivation of the Mo2C catalyst due to CO2 oxidation. The laser-catalytic DRM achieves high yields of H2 (14300.8 mmol h-1 g-1) and CO (14949.9 mmol h-1 g-1) with satisfactory energy efficiency (0.98 mmol kJ-1), providing a promising alternative for high-energy-consuming catalytic systems.

Transparent integrated pyroelectric-photovoltaic structure for photo-thermo hybrid power generation

Thermal losses in photoelectric devices limit their energy conversion efficiency, and cyclic input of energy coupled with pyroelectricity can overcome this limit. Here, incorporating a pyroelectric absorber into a photovoltaic heterostructure device enables efficient electricity generation by leveraging spontaneous polarization based on pulsed light-induced thermal changes. The proposed pyroelectric-photovoltaic device outperforms traditional photovoltaic devices by 2.5 times due to the long-range electric field that occurs under pulse illumination. Optimization of parameters such as pulse frequency, scan speed, and illumination wavelength enhances power harvesting, as demonstrated by a power conversion efficiency of 11.9% and an incident-photon-to-current conversion efficiency of 200% under optimized conditions. This breakthrough enables reconfigurable electrostatic devices and presents an opportunity to accelerate technology that surpasses conventional limits in energy generation.

New Nanophotonics Approaches for Enhancing the Efficiency and Stability of Perovskite Solar Cells

Over the past decade, the power conversion efficiency (PCE) of perovskite solar cells (PSCs) has experienced a remarkable ascent, soaring from 3.8% in 2009 to a remarkable record of 26.1% in 2023. Many recent approaches for improving PSC performance employ nanophotonic technologies, from light harvesting and thermal management to the manipulation of charge carrier dynamics. Plasmonic nanoparticles and arrayed dielectric nanostructures have been applied to tailor the light absorption, scattering, and conversion, as well as the heat dissipation within PSCs to improve their PCE and operational stability. In this review, it is begin with a concise introduction to define the realm of nanophotonics by focusing on the nanoscale interactions between light and surface plasmons or dielectric photonic structures. Prevailing strategies that utilize resonance-enhanced light-matter interactions for boosting the PCE and stability of PSCs from light trapping, carrier transportation, and thermal management perspectives are then elaborated, and the resultant practical applications, such as semitransparent photovoltaics, colored PSCs, and smart perovskite windows are discussed. Finally, the state-of-the-art nanophotonic paradigms in PSCs are reviewed, and the benefits of these approaches in improving the aesthetic effects and energy-saving character of PSC-integrated buildings are highlighted.

Significant hydrogen generation via photo-mechanical coupling in flexible methylammonium lead iodide nanowires

The flexoelectric effect, which refers to the mechanical-electric coupling between strain gradient and charge polarization, should be considered for use in charge production for catalytically driving chemical reactions. We have previously revealed that halide perovskites can generate orders of higher magnitude flexoelectricity under the illumination of light than in the dark. In this study, we report the catalytic hydrogen production by photo-mechanical coupling involving the photoflexoelectric effect of flexible methylammonium lead iodide (MAPbI3) nanowires (NWs) in hydrogen iodide solution. Upon concurrent light illumination and mechanical vibration, large strain gradients were introduced in flexible MAPbI3 NWs, which subsequently induced significant hydrogen generation (at a rate of 756.5 μmol g-1 h-1, surpassing those values from either photo- or piezocatalysis of MAPbI3 nanoparticles). This photo-mechanical coupling strategy of mechanocatalysis, which enables the simultaneous utilization of multiple energy sources, provides a potentially new mechanism in mechanochemistry for highly efficient hydrogen production.

Multimodal energy harvesting and catalysis of piezoelectric nanosheets for efficient and round-the-clock wastewater treatment

Solar-driven pollutants degradation is an important way for green wastewater treatment, but it is still limited by the intermittent solar flux. Here, we have prepared piezoelectric Bi4Ti3O12 (BTO) nanosheets with abundant physical properties, which can convert extensive solar energy, mechanical energy and temperature variation energy into electrical and chemical energy. It can be used for round-the-clock wastewater treatment by harvesting multi-modal energy. More importantly, the degradation rate of piezoelectric nanosheets can reach 153.4 × 10-3 min-1, and nanosheets can degrade many organic pollutants. In addition, we fabricate porous foam catalysts based on BTO-polydimethylsiloxane (PDMS) composite to prevent secondary contamination. Our results suggest that BTO nanosheets with photoelectric, piezoelectric and pyroelectric catalysis offer a potential approach for round-the-clock wastewater degradation by harvesting solar energy, ambient mechanical energy, and cyclic thermal energy.

Pulsed-Laser-Triggered Piezoelectric Photocatalytic CO2 Reduction over Tetragonal BaTiO3 Nanocubes

The recombination of photoinduced carriers in photocatalysts is considered one of the biggest barriers to the increase of photocatalytic efficiency. Piezoelectric photocatalysts open a new route to realize rapid carrier separation by mechanically distorting the lattice of piezoelectric nanocrystals to form a piezoelectric potential within the nanocrystals, generally requiring external force (e.g., ultrasonic radiation, mechanical stirring, and ball milling). In this study, a low-power UV pulsed laser (PL) (3 W, 355 nm) as a UV light source can trigger piezoelectric photocatalytic CO2 reduction of tetragonal BaTiO3 (BTO-T) in the absence of an applied force. The tremendous transient light pressure (5.7 × 107  Pa, 2.7 W) of 355 nm PL not only bends the energy band of BTO-T, thus allowing reactions that cannot theoretically occur to take place, but also induces a pulsed built-in electric field to determine an efficient photoinduced carrier separation. On that basis, the PL-triggered piezoelectric photocatalytic CO2 reduction realizes the highest reported performance, reaching a millimole level CO yield of 52.9 mmol g-1 h-1 and achieving efficient photocatalytic CO2 reduction in the continuous catalytic system. The method in this study is promising to contribute to the design of efficient piezoelectric photocatalytic reactions.

Pyroelectric catalytic performance of Sm3+-modified Pb(Mg1/3Nb2/3)O3-PbTiO3 for organic dyes: degradation efficiency, kinetics and pyroelectric catalytic mechanism

The development of photocatalysis is hindered, in part, by the quick recombination of photogenerated carriers and the instability of light sources. In this study, the problem of too-fast electron-hole pair compounding in photocatalysis is effectively regulated by the polarization field of pyroelectric materials using the pyroelectric method. Self-polarized pyroelectric materials that depend on temperature variations can generate usable electrical energy and polarized charge carriers to degrade organic pollutants. Pb(Mg1/3Nb2/3)O3-PbTiO3 (PMN-PT) is a relaxor ferroelectric material with spontaneous polarization characteristics. The PMN-0.30PT:1 mol%Sm3+ catalyst was prepared by applying the high-temperature solid-state reaction method. Under the dark condition and nine cold-hot cycles of 23 °C-68 °C, using H2O2-assisted PMN-0.30PT:1 mol%Sm3+ as a catalyst, the degradation rate of rhodamine 6G (10 mg L-1) was 94.3 ± 2.5%. In addition, the degradation rates of 88.52% and 64.32% were obtained for rhodamine B (10 mg L-1) and methylene blue (10 mg L-1), respectively. This study provides a new approach to the pyroelectric catalytic degradation of organic pollutants.

Enhanced Interfacial Charge Transfer/Separation By LSPR-Induced Defective Semiconductor Toward High Co2 RR Performance

Solar-driven reduction of CO2 emissions into high-value-added carbonaceous compounds has been recognized as a sustainable energy conversion way. The high-efficiency charge separation and effective activation are the critical issues in the process. The local plasma effect of metal and the vacancy of semiconductors in the metal-semiconductor heterostructure can solve this issue extensively. Herein, an oxygen vacancy photocatalyst containing uniform Ag nanoparticles (Ag-20@Nb2 O5- x ) is designed, which exhibits an excellent reduction performance and the CO yield can reach 59.13 µmol g-1 with high selectivity. The carrier migration is accelerated and the activation of CO2 is facilitated by the local surface plasmon effect and oxygen vacancy. Moreover, the photocatalytic CO2 reduction mechanism is revealed based on the density functional theory and in situ technology in detail. This work provides an in-depth understanding of the design of more ingenious metal-semiconductor photocatalysts to achieve more efficient charge transfer.