Solar Light Harvesting Research Articles

Dysprosium chromite nanoparticles: A promising photocatalyst for the remediation of ciprofloxacin and methylene blue from wastewater

A facile sol-gel synthesis method was employed to synthesize dysprosium chromite (DyCrO3) nanoparticles (NPs), which were subsequently calcined at 750 ∘C to investigate their structural, optical, and photocatalytic properties. Rietveld refinement of powder X-ray diffraction patterns revealed a single-phase orthorhombic structure for the DyCrO3 NPs, exhibiting good crystallinity and belonging to the Pbnm space group. Furthermore, Field Emission Scanning Electron Microscopy and Transmission Electron Microscopy imaging revealed a promising morphology with an average particle size of 30 ± 7 nm. Optical assessments indicated an energy band gap of 2.72 eV, suggesting potential for solar light harvesting as a photocatalyst. Mott-Schottky plots confirmed the n-type semiconductor behavior of the DyCrO3 NPs, and valence band X-ray photoelectron spectroscopy analysis supported these findings. Electronic band structure calculations showed a substantial conduction band minimum and a positive valence band maximum, essential for promoting oxygen reduction and oxidation reactions, respectively, which are crucial for photocatalytic activity. Moreover, the synthesized DyCrO3 NPs demonstrated significant potential as efficient photocatalysts, effectively decomposing the antibiotic ciprofloxacin (CIP) under solar light. Notably, the DyCrO3 NPs achieved 83 % degradation of CIP within 240 min of solar irradiation. Similarly, under identical conditions, the DyCrO3 NPs photocatalyst showed promise in degrading 70 % of the colored organic pollutant methylene blue (MB). Interestingly, during the first 120 min, the degradation of CIP was approximately 25 % greater than that of MB. The ability of DyCrO3 NPs to efficiently degrade both colored and colorless pollutants highlights the catalyst’s inherent photocatalytic nature, rather than merely relying on dye-sensitization effects. Furthermore, the presence of DyCrO3 NPs reduced the activation energy for CIP degradation from 31.657 kJ mol−1 K−1 to 20.846 kJ mol−1 K−1, providing additional evidence of their true catalytic efficacy. Apparent quantum yield values of 40 % for CIP and 35 % for MB degradation further illustrate their superior solar energy harvesting ability. A comprehensive mechanism was developed to explain the impressive photocatalytic performance of the synthesized NPs, highlighting their potential in degrading pharmaceutical antibiotics.

Fabrication of CdIn2S4/ZnS S-scheme heterojunction via in-situ phase transformation for boosting photocatalytic conversion of organic compounds

Developing efficient photocatalysts is one of green and low cost tactic for addressing the environmental deterioration and energy crisis. Therefore, it remains a fantastic and important strategy to design an efficient junction between different semiconductors for harvesting solar light, boosting the redox capability. Herein, the fabrication of ZnS in situ decorated CdIn2S4 (referred to as CIS-Zx) were prepared by converting ZnS particles on Cd2In4S surface by a facile cation exchange method during solvothermal synthesis. According to a series of PEC measurements and DFT calculations, the bending of band edge as well as the establishing of built-in electric field in the interface of CIS/ZnS heterojunction were concluded, causing the formation of in-situ S-scheme heterojunctions in CdIn2S4/ZnS. The in-situ S-scheme heterojunctions can effectively ameliorate the migration behaviors of photo-generated charges. Compared with pure CdInS4, ZnS and physically mixed CdIn2S4/ZnS, the CIS-Zxin-situ S-scheme heterojunction exhibits efficient photocatalytic activity and stability in the selective reduction of aromatic nitro compounds and oxidation of aromatic alcohols, it is hoped that this work will open up a new avenue for innovative applications of in-situ S-scheme heterojunctions.

Computational Study of Moth-Eye Structures for Silicon Solar Cells Lights Harvesting Improvement

Abstract Recently Moth-Eye nanostructure is widely used in solar cell light harvesting enhancement, in this computational work, three different designs; rectangular, triangular, and semi-circular structures were introduced as anti-reflect structures placed above a silicon solar cell, anti-reflected nanostructured modeled and optimized for silicon ultra-thin film solar cells using the finite difference time domain method for optical, and Lumerical devise software for electrical properties study. The effect of the geometrical dimension of the three structures was investigated. It is found that light-harvesting and solar cell performance can be enhanced by choosing a suitable structure and dimension for the suggested structure. The optimum efficiency enhancement achieved was by a semi-circular structure with a radius of 200nm from 8.81% to 11.95%.

Hybrid NenG/ZSM‐5 Towards Highly Selective and Efficient Photocatalysis for Generation of Leucodopaminechrome and Gluconic Acid Under Solar Light

AbstractGlucose, an abundant and renewable form of biomass, has garnered significant attention in research for its conversion into high‐value chemicals such as gluconic acid. Traditional methods for biomass transformation typically involve high energy input, elevated temperature, pressure, and costly systems. In contrast, photocatalysis emerges as a promising approach to produce organic molecules under mild conditions, harnessing energy from natural sunlight or lamps. This study presents the nitrogen‐enriched graphene with zeolite second Mobil–5 (NenG/ZSM‐5) photocatalyst, evaluated for generating high‐value chemicals (gluconic acid and leucodopaminechrome) under solar light irradiation. The NenG/ZSM‐5 photocatalyst, synthesized from nitrogen‐doped graphene and ZSM‐5, successfully converted dopamine into leucodopaminechrome (71.54 %) — a critical step in dopamine regeneration and transformed glucose into gluconic acid (85 %). The addition of ZSM‐5 to NenG provided stability and enhanced product selectivity. The outstanding performance of the NenG/ZSM‐5 photocatalyst can be attributed to its heightened solar light harvesting potential, appropriate energy band gap, and uniformly arranged π‐electron channels. This research focuses on solar conversion of glucose to gluconic acid and dopamine regeneration, with potential for further exploration in the research domain.

Organic Semiconductor-BiVO4 Tandem Devices for Solar-Driven H2O and CO2 Splitting.

Photoelectrochemical (PEC) devices offer a promising platform toward direct solar light harvesting and chemical storage through artificial photosynthesis. However, most prototypes employ wide bandgap semiconductors, moisture-sensitive inorganic light absorbers, or corrosive electrolytes. Here, the design and assembly of PEC devices based on an organic donor-acceptor bulk heterojunction (BHJ) using a carbon-based encapsulant are introduced, which demonstrate long-term H2 evolution and CO2 reduction in benign aqueous media. Accordingly, PCE10:EH-IDTBR photocathodes display long-term H2 production for 300 h in a near-neutral pH solution, whereas photocathodes with a molecular CO2 reduction catalyst attain a CO:H2 selectivity of 5.41±0.53 under 0.1 sun irradiation. Their early onset potential enables the construction of tandem PCE10:EH-IDTBR - BiVO4 artificial leaves, which couple unassisted syngas production with O2 evolution in a reactor completely powered by sunlight, sustaining a 1:1 ratio of CO to H2 over 96 h of operation.

Doping of photoactive TiO2 films by DC plasma electrolytic oxidation: Effect of transition metals

Several beneficial features maintain TiO2 in the top list of viable materials for photocatalytic purposes. However, its relatively large band-gap (3.0–3.2 eV) still hampers practical applications under sunlight. This work explores Direct Current (DC) Plasma Electrolytic Oxidation (PEO) of titanium as a fast, easily-scalable and single-step tool to synthesise doped TiO2 photoanodes with controlled morphology, crystalline structure and thickness. Zn-, Cu- and Fe-doped crystalline TiO2 films were obtained in H2SO4 aqueous solutions containing ZnSO4, CuSO4 and FeSO4 precursors, respectively. As-prepared TiO2 films showed a porous and homogeneous sponge-like surface morphology, typical of PEO-produced oxides, and a crystalline phase structure consisting of a mixture of anatase and rutile phases. The anatase content varied in the 54–100 % range and correspondingly the band-gap energy was in the 2.85–3.07 eV range. Doped oxides prepared with a low concentration of the metal precursors showed monochromatic incident-photon-to-current-efficiency (IPCE) values exceeding those obtained with pristine TiO2 by up to 24 %, best performing in the order Zn- > Cu- > Fe-doped TiO2. Photocurrent under polychromatic UV-Vis irradiation showed an analogous trend and the estimated efficiency of solar-light harvesting was in the 0.3–4 % range, with Zn- ≈ Cu- > Fe-doped TiO2. Although the superior performance of the PEO-prepared metal-doped TiO2 could not be fully confirmed by photoelectrocatalytic oxidation tests of organics, the present investigation showed the viability of DC PEO for the synthesis of metal-doped TiO2 photoanodes.

Polyimide/Ag2WO4 Z-Scheme Heterojunction for Efficient Photocatalytic Degradation of Tetracycline.

It is of great significance to construct a Z-scheme heterojunction for improving solar light harvesting and achieving efficient separation of photogenerated carriers and then enhancement of the photocatalytic performance of semiconductor photocatalysts. Herein, the direct Z-scheme PI/Ag2WO4 heterojunction was designed and prepared according to the band edge potentials of the semiconductor. Due to the fact that the Z-scheme structure not only endowed the PI/Ag2WO4 composites with efficient separation of photogenerated electron-hole pairs but also reserved the redox ability of the valence band and conduction band of monophase catalysts, the 50% PI/Ag2WO4 heterojunction exhibited excellent photocatalytic activity, which were 2.9 and 1.5 times those of the PI and Ag2WO4 photocatalysts, respectively. The photocatalytic reaction mechanism of PI/Ag2WO4 composites was confirmed by the results of TEM, UV-vis, XPS, and EPR experiments. This work provides a feasible strategy to design high-performance photocatalysts in the field of practice purification of wastewater.

Heterojunction characteristics and photoelectrochemical performance of TiO2 nanorods sensitized by zeolitic imidazolate framework

Traditional photocatalysts suffer from inferior utilization of solar light. Therefore, developing novel photocatalyst for better solar light harvesting is much required in the wake of current environmental problems arising from conventional energy technologies. Here we report synthesis and characterization of photocatalysts based on TiO2 nanorods (TNR) and Zeolitic Imidazolate Framework-9 (ZIF-9) and their photoelectrochemical properties. The TNRs were sensitized by ZIF-9 through solvothermal method. The presence of ZIF-9 on TNR formed a p-n heterojunction which assisted in initiating efficient charge separation and promoting injection of these carriers into the electrolyte. The heterojunction catalysts also exhibited enhanced optical properties in terms of extended absorption with reduced bandgap in comparison to the TNR film. The aforementioned properties manifested in improved photoelectrochemical performance with a current density of 0.94 mA/cm2, which is four times better than TNR and an applied bias photon to current efficiency (ABPE) of 0.27 %, which is five times better than TNR film alone. These superior properties of the processed ZIF-TNR demonstrate their potential for photoelectrochemical catalysis, thus paving the way for green hydrogen generation.

Neodymium-doped nickel cobaltite reinforced with 2D MXene nanocomposite (Nd-NiCo2O4/MXene) for enhanced photocatalytic degradation of the organic pollutants

In the quest for sustainable strategies for environmental remediation and wastewater treatment, composite material-based visible light-responsive photocatalysis has emerged as a highly efficient method that is not only facile but also economical. Herein, we have synthesized pure (NiCo2O4) and Nd-doped (Nd-NiCo2O4) nickel cobaltite nanoparticles and incorporated doped material on 2D MXene to fabricate nanocomposite (Nd-NiCo2O4/MXene). The prepared samples were characterized to exploit the effect of Nd-doping and composite formation on structural, electrical, and optical properties. The photocatalytic potential of composite material was investigated by targeting malachite green and pendimethalin. In comparison to pure and doped materials, the nanocomposite demonstrated superior photocatalytic efficiency for the degradation of targeted pollutants. This enhanced catalytic activity is attributed to the synergism of rare earth metal doping and composite formation which result in enhanced absorption in visible light and lower coupling of charge carriers. Systematic studies revealed the promising potential of the Nd-NiCo2O4/MXene nanocomposite for solar light harvesting in wastewater remediation applications.

Improvement power conversion efficiency in graphene quantum dot by functionalization and heteroatom doping used in solar cell

First-principles density functional theory (DFT) was adopted for investigating the influence of adatoms (S, Si, Al) upon the graphene quantum dot functionalized with the carboxyl group (CO2H-GQD) in order to find novel materials due to unique optical (redshift) and electronic (lower bandgap) properties for utilization in quantum dot solar cells (QDSCs). For the sake of examining the alteration in the electronic attributes due to the insertion of adatoms, the bandgaps, the LUMO and the HOMO were examined using the density functional B3LYP and the basis set 6-31G. For the sake of examining the charge separation and electron injection in the un-doped and doped CO2H-GQD, we scrutinized the charge transport, molecular electrostatic potential (MESP) and the binding mechanism. The optical attributes demonstrated a broad spectrum in the visible range favorable towards harvesting solar light. We also investigated the parameters of solar cells such as efficiency (η), short circuit current density (Jsc), fill factor (FF), open circuit voltage (Voc) in order for the sake of examining the use of adatom-doped CO2H-GQD in QDSCs. There was an increase in the efficiency of S-doped, Si-doped, and Al-doped CO2H-GQD. Doping the CO2H-GQD led to the maximum efficiency since electron donating nature was more, thereby injecting more electrons in the surface of TiO2. The results demonstrated that such GQD-based sensitizers can be used effectively in QDSCs.

Advances in functionalized annihilators to extend triplet–triplet annihilation upconversion performances

Triplet–triplet annihilation upconversion (TTA-UC) has made major advances in many emerging fields in recent years, such as solar light harvesting, photocatalysis, biological imaging, and sensing. TTA-UC consists of photosensitizers and annihilators. In addition to acting as emitters, chemical modification of annihilators has expanded their roles to include the formation of organic gel to avoid oxygen-mediated triplet quenching, amplifying the asymmetry factor of circularly polarized luminescence, constructing an upconversion sensor as recognition units, serving as photoremovable protecting groups, and photocatalysts to realize long-wavelength light-driven organic transformations. Here, we will focus on the significant applications of functionalized annihilators other than photoluminescence, which are manifested via chemical modification with other functional units. Finally, we will elaborate on the existent issues with TTA-UC, including challenges in molecular design, material development, and emerging field applications. In accordance with our research experience, we will propose potential solutions.

Synthesis of nitrogen-doped graphene coupled acid fuchsin photocatalyst turns aryl-vinyl into aromatic aldehydes under visible light

A schematic strategy is presented to overcome the problem of low photocatalytic performance of graphene. Herein, we synthesized nitrogen-doped graphene (NDG)-coupled acid fuchsin (AF) photocatalyst, i.e.; NDGCAF photocatalyst. The NDGCAF photocatalyst has excellent solar light harvesting ability, band gap suitability, and high molar extinction coefficient than the NDG photocatalyst. Due to these properties, the NDGCAF photocatalyst has the ability to oxidize aryl-vinyl into aryl-vinyl-aldehyde under the irradiation of visible light. In this context, it exhibited the utmost conversion efficiency of aryl-vinyl to aryl-vinyl-aldehyde with a good yield of 98.15% . Current research highlights the significant application of NDGCAF light-harvesting photocatalysts in the research field of organic transformations.

Sonochemical surface modification of a novel Sm2O3@g-C3N4@Bi2O3 ternary hybrid photocatalyst exhibiting efficient solar light harvesting: Degradation of Azure b and photoelectrochemical water splitting

Engineered Z-scheme photocatalysts have a strong redox activity while also reducing the annihilation of light-induced charge bearers. In this investigation, a solid state twin Z-scheme Sm2O3@g-C3N4@Bi2O3 nanocomposite has been successfully prepared employing bismuth (III) nitrate, samarium chloride and urea as precursor chemicals in a single co-calcination procedure followed by sonochemical surface modification. The formation of flower like multiphasic material is confirmed from SEM and HRTEM images. BET findings suggested the enhancement in specific surface area of Sm2O3@g-C3N4@Bi2O3 and reduced band gap from UV–visible data. Photoluminescence results confirmed the reduction in rate of charge carrier recombination of Sm2O3@g-C3N4@Bi2O3. Presence of samarium is confirmed from XPS analysis. Under direct solar radiation, the surface modified Sm2O3@g-C3N4@Bi2O3 hybrid demonstrated amplified photo-assisted catalytic activity for the degradation of Azure B (AzB) than pristine g-C3N4 and their binary composite Sm2O3@g-C3N4. It is possible to attribute the better solar light absorption, higher separation efficacy of photo-promoted electron-holes to the amplified photo-assisted degradation performance of the Sm2O3@g-C3N4@Bi2O3 composite. The photodegradaton of AzB follows pseudo-first order kinetics and the observed rate constants are 0.0014, 0.0026, and 0.0316 min−1 for g-C3N4, Sm2O3@g-C3N4, and Sm2O3@g-C3N4@Bi2O3 ternary composite. The nanocomposite also demonstrates good stability and recyclability. A unique solid-state twin Z-scheme photocatalytic pathway was also hypothesized in light of the findings. The fabricated ternary hybrid shown efficient photoelectrochemical water splitting reaction for H2 and O2 generation.

Pleurosigma strigosum diatom frustule as a natural, multi-functional photonic platform

Nature provides various organisms with ordered or quasi-ordered dielectric nanostructures that enable several animals, plants, and protists to manipulate light, optimizing inter- and intra-species communication, camouflage, or solar light harvesting. In particular, diatom microalgae possess nanostructured silica cell walls, known as frustules, which efficiently interact with optical radiation through multiple diffractive, refractive, scattering, waveguiding, and frequency down-conversion mechanisms. These properties contribute to diatoms’ efficiency in photosynthesis, UV tolerance, and possibly influence the phototaxis mechanisms of motile species. In our study, we utilized several imaging, spectroscopic, and numerical techniques to explore the optical functionalities of individual frustule components in the pennate, motile diatom Pleurosigma strigosum. We discuss the implications of frustule photonic properties on the living cell, and envision the exploitation of these properties in multifunctional, bio-derived photonic devices.

Designing Metasurfaces for Efficient Solar Energy Conversion.

Metasurfaces have recently emerged as a promising technological platform, offering unprecedented control over light by structuring materials at the nanoscale using two-dimensional arrays of subwavelength nanoresonators. These metasurfaces possess exceptional optical properties, enabling a wide variety of applications in imaging, sensing, telecommunication, and energy-related fields. One significant advantage of metasurfaces lies in their ability to manipulate the optical spectrum by precisely engineering the geometry and material composition of the nanoresonators' array. Consequently, they hold tremendous potential for efficient solar light harvesting and conversion. In this Review, we delve into the current state-of-the-art in solar energy conversion devices based on metasurfaces. First, we provide an overview of the fundamental processes involved in solar energy conversion, alongside an introduction to the primary classes of metasurfaces, namely, plasmonic and dielectric metasurfaces. Subsequently, we explore the numerical tools used that guide the design of metasurfaces, focusing particularly on inverse design methods that facilitate an optimized optical response. To showcase the practical applications of metasurfaces, we present selected examples across various domains such as photovoltaics, photoelectrochemistry, photocatalysis, solar-thermal and photothermal routes, and radiative cooling. These examples highlight the ways in which metasurfaces can be leveraged to harness solar energy effectively. By tailoring the optical properties of metasurfaces, significant advancements can be expected in solar energy harvesting technologies, offering new practical solutions to support an emerging sustainable society.

A series of four-coordinate heteroleptic copper(I) complexes with diimine and β-diketiminate ligands

In this paper, a series of heteroleptic bis-chelate copper(I) complexes of the general formula Cu(N^N)(NacNacR), where N^N is the diimine ligand and NacNacR is the β-diketiminate ligand are introduced. The complexes are easily prepared by reacting NacNac ligands with CuOtBu in the presence of diimine ligands. The molecular structures of all complexes are characterized by NMR spectroscopy and X-ray crystallography. The studies of cyclic voltammetry and UV–vis absorption spectra show that the HOMO and the LUMO energy level can be tailored by changing the substitution pattern of each ligand. The oxidation potential is dependent on the NacNac ligand, and the reduction potential shows the dependence on the diimine ligand. Tunable redox potentials and a wide range of visible absorption can make these copper(I) complexes promising candidates for applications in solar light harvesting.

Preparation of PbBiO2I ultrathin nanosheets with rich oxygen vacancies for enhanced visible-light-driven photocatalytic activities

Photocatalytic oxidation technology is deemed as a prospective approach to settle the global environmental crisis. Nevertheless, the photocatalytic performance is limited by the insufficient solar light harvesting ability and disappointing charge carrier separation efficiency of photocatalysts. Herein, PbBiO2I ultrathin nanosheets with tunable oxygen vacancy (OV) concentrations were successfully fabricated via ionothermal process. The crystal structure, morphology and photoelectrochemical properties of the acquired catalysts were systematically studied. The photocatalytic degradation results demonstrate that rich oxygen vacancy (ROV) PbBiO2I possesses the highest photocatalytic degradation activity, which is about 2.9 and 35.0 times higher than those of deficient oxygen vacancy (DOV) PbBiO2I and bulk PbBiO2I in rhodamine B (RhB) degradation. The enhanced visible-light absorption region arising from bulk oxygen vacancy and surface oxygen vacancy can serve as highly active sites for catalytic reaction. This contributes to enriching electrons to accelerate oxygen molecular activation and boost charge separation. Additionally, superoxide radicals (O2•-) and holes (h+) are proved to be the major reactive species during photocatalytic process. By which, a feasible photocatalytic mechanism was primarily proposed. This research can offer a new avenue for developing bismuth-based defective photocatalyst in the field of environmental remediation.

Enhancing the performance of quantum dot solar cells through halogen adatoms on carboxyl edge-functionalized graphene quantum dots

This research has been conducted to find new, high-performing, safe, and suitable materials for use in quantum dot solar cells (QDSCs). Specifically, impact of halogen adatoms (Br, Cl, and F) on carboxyl edge-functionalized graphene quantum dot (CO2H-GQD) has been investigated employing DFT-based first-principles computations. We analyzed energy gaps (Eg), LUMO, and HOMO to determine how the foreign atom affects electronic features of material, employing hybrid functional B3LYP with a 6-31G basis set. In order to investigate charge separation and electron injection in both doped and undoped CO2H-GQD, we examined charge transfer (CT), molecular electrostatic potential (MESP), and binding mechanism. Optical attributes also indicate a wide spectrum in visible range, making it suitable for harvesting solar light. Furthermore, we evaluated solar cell parameters, including efficiency (η), short circuit current density (Jsc), fill factor (FF), and open circuit voltage (Voc) to assess potential usage of adatom-doped CO2H-GQD in quantum dot solar cell. Subsequent to Br, Cl, and F substitutional doping, value of η for CO2H-GQD increased. In case of F doping, we achieved maximum η, which has electron-donating nature and a larger radius, allowing it to inject more electrons into titanium dioxide (TiO2) surface. Based on our research, we have determined that these recently discovered sensitizers built upon GQD exhibit considerable potential for use in QDSCs.

Solar harvesting through multiple semi-transparent cadmium telluride solar panels for collective energy generation

Among major energy conversion methods, photovoltaic (PV) solar cells have been the most popular and widely employed for a variety of applications. Although a PV solar panel has been shown as one of the most efficient green energy sources, its 2D surface solar light harvesting has reached great limitations as it requires large surface areas. There is, therefore, an increasing need to seek solar harvest in a three-dimensional fashion for enhanced energy density. In addition to a conventional 2D solar panel in the x-y area, we extend another dimension of solar harvesting in the z-axis through multiple CdTe solar panels arranged in parallel. The high transparency allows sunlight to partially penetrate multiple solar panels, resulting in significantly increased solar harvesting surface area in a 3D fashion. The advantages of the 3D multi-panel solar harvesting system include: i) enlarged solar light collecting surface area, therefore increased energy density, ii) the total output power from multiple panels can exceed that of the single panel, and iii) significantly reduced surface area needed for densely populated cities. With five CdTe solar panels of different transparencies in parallel, the multilayer system can produce collective output power 233% higher than that of the single solar panel under the same surface area when arranged in descending (i.e., PV panel with the highest transparency on top and lowest at bottom). The PCE of the multi-panel system has also increased 233% in descending order indicating the viability of 3D solar harvesting. The multi-panel system will dimensionally transform solar harvesting from 2D to 3D for more efficient energy generation.

Highly regular nanogratings on amorphous Ge films via laser-induced periodic surface sublimation

Despite the fact that monocrystalline germanium (Ge) was historically the first material where formation of laser-induced periodic surface structures (LIPSSs) was observed in 1965 and then extensively studied, practically relevant thin films of amorphous Ge (a-Ge) were occasionally ignored by these studies so far. Here, highly regular LIPSSs were observed on the surface of magnetron-sputtered a-Ge films under near-IR femtosecond laser exposure. Formation of these regular structures was explained by excitation and interference of the surface waves at the interface of photoexcited Ge that was confirmed by performed calculations and full-wave simulations. At the same time, remarkable structural regularity of these LIPSSs unveiled their ablation-free formation scenario involving laser-driven oxidation of the Ge followed by ultra-clean sublimation of the oxide. Laser patterning in vacuum was found to regulate oxidation/sublimation rates of the a-Ge and its oxide improving the structure quality and opening pathways for practical applications in optoelectronics, solar light harvesting and near-IR photonics.