Miguel Gomez-Mendoza

Interfacial nanostructuring is an effective strategy for improving the performance of organic–inorganic photocatalysts, although it cannot necessarily overcome the intrinsic excited-state limitations of the organic semiconductor.

Transition‐metal incorporation is widely employed to enhance the photoelectrochemical performance of BiVO ₄ photoanodes, yet how the local incorporation environment governs charge‐carrier dynamics remains poorly understood. Here, we establish a structure‐function relationship between the local environments of Fe, Co, and Ni and the resulting charge‐dynamics in BiVO ₄ . Combining synchrotron‐based x‐ray spectroscopies with femtosecond‐to‐microsecond photophysical measurements, we show that all transition metals improve water oxidation activity relative to pristine BiVO ₄ , following the trend (Ni > Fe > Co) > BiVO ₄ . Fe and Co predominantly adopt heterogeneous, oxide‐like local environments associated with weaker and more spatially heterogeneous coupling to the BiVO ₄ framework, resulting in moderate improvements in charge separation. In contrast, Ni forms highly oxidized, locally octahedrally coordinated Ni–O units that exhibit stronger electronic coupling with the BiVO ₄ framework, modifying the V–O electronic structure, suppressing charge localization and recombination, and extending carrier lifetimes across multiple timescales. Operando x‐ray absorption further reveals that incorporated Ni species remain electronically responsive under working conditions, linking their local electronic structure to photogenerated charge accumulation. These findings demonstrate that the photoelectrochemical behavior of transition‐metal‐modified BiVO ₄ is governed by the nature of metal–host electronic coupling rather than metal identity alone, providing a general design principle for oxide photoanodes.

Transition‐metal incorporation is widely employed to enhance the photoelectrochemical performance of BiVO ₄ photoanodes, yet how the local incorporation environment governs charge‐carrier dynamics remains poorly understood. Here, we establish a structure‐function relationship between the local environments of Fe, Co, and Ni and the resulting charge‐dynamics in BiVO ₄ . Combining synchrotron‐based x‐ray spectroscopies with femtosecond‐to‐microsecond photophysical measurements, we show that all transition metals improve water oxidation activity relative to pristine BiVO ₄ , following the trend (Ni > Fe > Co) > BiVO ₄ . Fe and Co predominantly adopt heterogeneous, oxide‐like local environments associated with weaker and more spatially heterogeneous coupling to the BiVO ₄ framework, resulting in moderate improvements in charge separation. In contrast, Ni forms highly oxidized, locally octahedrally coordinated Ni–O units that exhibit stronger electronic coupling with the BiVO ₄ framework, modifying the V–O electronic structure, suppressing charge localization and recombination, and extending carrier lifetimes across multiple timescales. Operando x‐ray absorption further reveals that incorporated Ni species remain electronically responsive under working conditions, linking their local electronic structure to photogenerated charge accumulation. These findings demonstrate that the photoelectrochemical behavior of transition‐metal‐modified BiVO ₄ is governed by the nature of metal–host electronic coupling rather than metal identity alone, providing a general design principle for oxide photoanodes.

Herein, we investigated how the introduction of different metal salts during the synthesis of bismuth oxychloride affects its electronic structure, revealing that the nature of the metal salt plays a key role in determining the resulting properties. Several species (Mo, Se, W, V, Ti, Mn, Hg, and Pb) were added to affect the precipitation of the BiOCl photocatalysts. Prepared samples were investigated concerning their crystal structure, elemental composition, morphology, surface area, and optical properties, which were discussed considering possible effects of Bi substitution from the density functional theory calculations. Ti and Hg influence only the crystal growth and morphology. Mo, W, and V, as metallates, shift the absorption to the visible region, but the resulting photocatalytic activity was hindered. Pb ²⁺ and Mn ²⁺ ions substitute for Bi, acting as acceptor defects. Moreover, MnCl ₂ lead to significant crystal growth and formation of well‐defined {100}, {110}, {101}, and {111} facets. The BiOCl:Mn sample shows increased activity, connected with conduction band (CB) shift and enhanced O ₂ reduction to ∙O ₂ ⁻ . Introduction of SeO ₃ ²⁻ deposits Se ⁴⁺ /S ⁰ species on the surface, leading to the formation of smaller, well‐defined rectangular BiOCl crystals. Surface selenium acts as electron traps, increasing the charge carriers lifetime and promoting 2‐electron reduction of O ₂ to H ₂ O ₂ .

This work reports the synthesis and characterization of two di-amino-functionalized dyes based on BODIPY and BOPHY, designed as dual optical sensors for pH and metal ions, with particular selectivity toward Cu²⁺. Owing to the presence of amino groups, both compounds exhibit environment-dependent fluorescence modulation, showing a reversible “on–off” fluorescence behavior in response to acidic conditions and metal coordination. Spectroscopic studies reveal that under acidic pH (below 4), both dyes undergo significant changes in absorption and exhibit enhanced fluorescence, attributed to protonation of the amino groups and a reduction in nitrogen pyramidal inversion. Moreover, both compounds display distinct optical responses upon exposure to various metal salts, with BODIPY showing selective and transient fluorescence activation in the presence of copper sulfate under near-neutral conditions. Detailed analyses suggest the formation of three distinct species during the Cu²⁺ interaction: (I) the native dye, (II) a highly fluorescent intermediate complex, and (III) a non-emissive decomposition product. The kinetics and stability of these species were found to be highly dependent on the solvent environment, particularly its protic/aprotic nature. These findings underscore the potential of these small, structurally simple dyes as efficient dual-function sensors, offering broad applicability in environmental monitoring, biological imaging, and chemical sensing.

Herein, the synthesis of a phenazine‐based ultrananostructured conjugated porous polymer (UN_IEP‐27) is described, using high‐performance microfluidic techniques (HPMT). This approach enables the obtention of small particle sizes, high homogeneity, good dispersibility, large surface areas, and therefore improved processability. The phenazine moiety provides redox‐active sites to the polymer. These features allow the fabrication of high‐quality thin films for photoelectrochemical characterization and, more importantly, significantly enhance the photocatalytic performance of its TiO ₂ hybrid. The hybrid material, UN_IEP‐27@T10 (10 wt.% polymer), reaches hydrogen evolution rates of 4.1 mmol g ⁻ ¹ h ⁻ ¹ (ƺ = 1.52%) under laboratory conditions, and 0.11 mmol g ⁻ ¹ h ⁻ ¹ (ƺ = 0.58%) at solar‐pilot scale representing 51‐fold and 5.5‐fold improvements over bare TiO ₂ , respectively. Moreover, after repeating the experiments under inert atmosphere for consecutive days, the activity increases, reaching up to 4.8 mmol g ⁻ ¹ h ⁻ ¹ (ƺ = 1.76%) and 0.34 mmol g ⁻ ¹ h ⁻ ¹ (ƺ = 1.81%) at lab and pilot scale, respectively. This behavior is attributed to the redox cycling of the phenazine unit, which undergoes reversible transitions between phenazine and its more photoactive form, dihydrophenazine. These results stand among the best reported for conjugated porous polymer (CPP)‐based hybrids for hydrogen photocatalysis.

The ozonolytic deconstruction of aromatics remains a challenge in organic chemistry. Ozone preferentially reacts with alkenes over arenes, meaning that once the initial aromatic cleavage occurs, the dearomatized products are inherently more reactive than the starting materials. Consequently, the process cannot be halted, resulting in full oxidation. Addressing this challenge requires subverting intrinsic rules of chemoselectivity to transform a less reactive substrate in the presence of a more reactive one. We demonstrate that this concept can be achieved by using photoexcited nitroarenes. Crucial to the success of this chemoselective process is the use of a nitroarene that is preferentially excitable to a triplet π,π* state over the n,π* state. This switch in excited-state configuration provides an otherwise inaccessible manifold, in which oxidative cleavage is diverted toward aromatics in the presence of alkenes.

Charge‐transfer complex formation within the pores of porous polymers is an efficient way to tune their electronical properties. Introduction of electron accepting guests to the electron donating hosts to conduct their p‐doping is intensively studied in this context. However, the vice versa scenario, n‐doping by treating the electron deficient (i.e., n‐type) porous polymers with electron donating dopants, is rare. In this work, synthesis of an n‐type phenazine based conjugated microporous polymer and its exposure to strong electron donating tetrathiafulvalene (TTF) dopants are presented. The fundamental physical characterizations (e.g., elemental analysis, gas sorption) showed that the vacuum impregnation technique is a good approach to load the guest molecules inside the pores. Moreover, the formation of charge‐transfer complexes between the phenazine building blocks of the polymeric network and TTF dopants are confirmed via spectral techniques such Fourier transform infra‐red, UV–vis, steady‐state/time‐resolved photoluminescence, and transient absorbance spectroscopies. Effect of the doping to the electronical properties is monitored by employing photoelectrochemical measurements, which showed lower charge‐transfer resistivity and nearly doubled photocurrents after the doping. The study is, therefore, an important advancement for the applicability of (n‐type) porous polymeric materials in the field of photo(electro)catalysis and organic electronics.

Here, the use of high‐performance microfluidic techniques (HPMT) is reportedto afford conjugated porous polymer (CPPs) with smaller particle size and narrower particle size dispersion than the obtained by miniemulsion methodology. Specifically, polymers based on BODIPY or BOPHY dyes are synthesized by HPMT conditions and conventional miniemulsion conditions. The polymer textural properties from HPMT are notably improved, giving rise to high‐quality thin films that are photoelectrochemically characterized. Furthermore, hybrid materials of CPPs synthesized by HPMT and TiO₂ inorganic semiconductor revealed enhanced photocatalytic activity in the hydrogen evolution reaction (HER). The most active hybrid UN_IEP‐7@T‐10 photocatalyst, containing 10 wt% polymer loading, achieved a hydrogen evolution rate of 3.10 mmol g⁻¹ h⁻¹ (ƺ = 1.13%), which is threefold higher than that of its non‐nanostructured from bulk synthesis, two‐times greater than its nanostructured by conventional miniemulsion techniques and even surpassed by 39‐times the performance of bare TiO₂. It is noteworthy that both photoluminescence lifetime (τ_PL) and transient lifetime (τ_T) are not affected by the nanoestructuration of CPPs, which agrees with the preservation of the chemical structure by both synthetic methodologies. The employment of HPMT as nanostructuration strategy clearly supports the obtaining of more processable polymers for a wide range of energy applications.