Noble metal porphyrin derivatives bearing carboxylic groups: Synthesis, characterization and photophysical study

Highly efficient light-driven hydrogen evolution utilizing porphyrin-based nanoparticles

We developed dye-sensitized photocatalytic systems (DSPs) by utilizing porphyrins as a photosensitizer (PS) or as a photosensitizer-catalyst (PS/CAT) upon their chemisorption onto platinum-doped titanium dioxide nanoparticles (Pt-TiO2 NPs). The DSPs coated with Pt-Tc3CP (PS/CAT entity) exhibited a record-high stability (25 500 TONs) and H2 evolution activity (707 mmol g-1 h-1) compared to similar DSPs in the literature.

A Modified Triple-Diode Model Parameters Identification for Perovskite Solar Cells via Nature-Inspired Search Optimization Algorithms

Recently, perovskite solar cells (PSCs) have been widely investigated as an efficient alternative for silicon solar cells. In this work, a proposed modified triple-diode model (MTDM) for PSCs modeling and simulation was used. The Bald Eagle Search (BES) algorithm, which is a novel nature-inspired search optimizer, was suggested for solving the model and estimating the PSCs device parameters because of the complex nature of determining the model parameters. Two PSC architectures, namely control and modified devices, were experimentally fabricated, characterized and tested in the lab. The I–V datasets of the fabricated devices were recorded at standard conditions. The decision variables in the proposed optimization process are the nine and ten unknown parameters of triple-diode model (TDM) and MTDM, respectively. The direct comparison with a number of modern optimization techniques including grey wolf (GWO), particle swarm (PSO) and moth flame (MFO) optimizers, as well as sine cosine (SCA) and slap swarm (SSA) algorithms, confirmed the superiority of the proposed BES approach, where the Root Mean Square Error (RMSE) objective function between the experimental data and estimated characteristics achieves the least value.

Controlling Solar Hydrogen Production by Organizing Porphyrins

In this study, a highly efficient photocatalytic H₂ production system is developed by employing porphyrins as photocatalysts. Palladium and platinum tetracarboxyporphyrins (PdTCP and PtTCP) are adsorbed or coadsorbed onto TiO₂ nanoparticles (NPs), which act as the electron transport medium and as a scaffold that promotes the self-organization of the porphyrinoids. The self-organization of PdTCP and PtTCP, forming H- and J-aggregates, respectively, is the key element for H₂ evolution, as in the absence of TiO₂ NPs no catalytic activity is detected. Notably, J-aggregated PtTCPs are more efficient for H₂ production than H-aggregated PdTCPs. In this approach, a single porphyrin, which self-organizes onto TiO₂ NPs, acts as the light harvester and simultaneously as the catalyst, whereas TiO₂ serves as the electron transport medium. Importantly, the concurrent adsorption of PdTCP and PtTCP onto TiO₂ NPs results in the most efficient catalytic system, giving a turnover number of 22,733 and 30.2 mmol(H₂ ) g(cat)^-1 .

A versatile route to fabricate single atom catalysts with high chemoselectivity and regioselectivity in hydrogenation

Preparation of single atom catalysts (SACs) is of broad interest to materials scientists and chemists but remains a formidable challenge. Herein, we develop an efficient approach to synthesize SACs via a precursor-dilution strategy, in which metalloporphyrin (MTPP) with target metals are co-polymerized with diluents (tetraphenylporphyrin, TPP), followed by pyrolysis to N-doped porous carbon supported SACs (M₁/N-C). Twenty-four different SACs, including noble metals and non-noble metals, are successfully prepared. In addition, the synthesis of a series of catalysts with different surface atom densities, bi-metallic sites, and metal aggregation states are achieved. This approach shows remarkable adjustability and generality, providing sufficient freedom to design catalysts at atomic-scale and explore the unique catalytic properties of SACs. As an example, we show that the prepared Pt₁/N-C exhibits superior chemoselectivity and regioselectivity in hydrogenation. It only converts terminal alkynes to alkenes while keeping other reducible functional groups such as alkenyl, nitro group, and even internal alkyne intact.

The general synthesis of single atom catalysts (SACs) is of broad interest to chemists but remains a formidable challenge. Here, with the precursor-dilution strategy, the authors successfully prepare 24 different SACs and the Pt SACs exhibit superior chemo- and regio-selectivity in hydrogenation.

Ru(II) porphyrins as sensitizers for DSSCs: Axial vs. peripheral carboxylate anchoring group

In this study, two porphyrin chromophores metallated with ruthenium, RuTBP and RuTBPPy, were prepared and studied as sensitizers in dye-sensitized solar cells (DSSCs). The difference between the two dyes is the position (axial vs. peripheral) of the carboxylic anchoring group. This work examines the impact of this variation towards the optical, electrochemical and photovoltaic performance of DSSCs. The thorough photophysical and photovoltaic measurements indicated that the peripherally substituted sensitizer (RuTBP) presented higher photovoltaic performance compared to RuTBPPy. More specifically, DSSCs sensitized with RuTBP and RuTBPPy displayed an overall power conversion efficiency (PCE) of 5.12% and 4.08%, respectively. The higher PCE value of the DSSC sensitized with RuTBP is mainly attributed to the enhancement of [Formula: see text] and FF values. These factors were enhanced due to the efficient dye regeneration process, the suppression of back-charge recombination reactions and the longer electron lifetimes as evidenced from the electrochemical impedance spectra.

Tetrakis(ethyl-4(4-butyryl)oxyphenyl)porphyrinato zinc complexes with 4,4'-bpyridin: synthesis, characterization, and its catalytic degradation of Calmagite

This work reports on the synthesis and characterization of a new porphyrins complex:[Zn(TEBOP)(4,4'-bpy)](4,4'-bipyridine)(5,10,15,20-(tetraethyl-4(4-butyryl)oxyphenyl)porphyrinato)zinc(ii) (3). Single crystal X-ray diffraction, photophysical and electrochemical characteristics were studied. The prepared complex, penta-coordinated zinc(ii) porphyrin derivatives shows moderate ruffling distortion and the zinc atom is nearly planar with the porphyrin core. Tolyl and ethyl-4(4-butyryl)oxyphenyl) moieties at the meso positions present a bathochromic shift of the absorption bands, and a notable increase in the absorption coefficient of the Q(0,0) and Q(0,1) bands was observed with a higher fluorescence quantum yield and lifetime compared with the free base porphyrin. The electrochemical investigation shows a reversible reduction of the synthesized complexes. The catalytic power and the adsorption properties of the prepared complexes were studied for Calmagite degradation, an azoic organic dye. The results reveal that the studied compounds could be used as catalysts for the decolourisation of dyes in the presence of H2O2.

Artificial hemes for DSSC and/or BHJ applications

In this review paper a summary of our studies is presented concerning the power conversion efficiency of DSSC and BHJ based on porphyrin hybrid materials.

Synthesis, photophysical characterization, and photoelectrochemical evaluation of a palladium porphyrin sensitizer for TiO2-based dye-sensitized solar cells

An unsymmetrical (A3B) palladium porphyrin bearing a cyanoacrylic acid at one meso position has been synthesized for evaluation as a photosensitizer in dye-sensitized solar cells based on titanium dioxide ( TiO 2) as a comparison to other metalloporphyrins and as a proxy for other potential triplet-state photosensitizer compounds. The synthesis of this palladium porphyrin has provided new insight into the mechanism and product distribution of decarboxylative hydrolysis of malonic acid when attached at the porphyrin meso position. A crystal structure determination for a meso-formyl palladium porphyrin has been determined, showing saddle-distortion of the porphyrin core. The photophysical behavior of the palladium porphyrin sensitizer and its performance in photoelectrochemical cells are described and interpreted in the context of bimolecular excited state quenching pathways including oxygen sensitization, triplet–triplet annihilation and electron transfer events. Palladium porphyrins are proposed as a sensitizer class with potential for high efficiency dye-sensitized solar cells, but with the caveat that some overpotential for electron injection is necessary to compete against the multiple decay pathways that are specially available to triplet state photosensitizers.