Institute of Physical Chemistry

In addition to storing molecular oxygen, myoglobin catalyzes peroxidase-like reactions involving high-valency iron(IV)-oxo species that support one-electron oxidations on a range of substrates at an open active site. In select metalloenzymes, long-range electron transfer can be mediated by hole-hopping pathways composed of aromatic residues that act as relay stations for oxidative equivalents. However, it remains unclear how sequence variations could introduce or alter such catalytic mechanisms in myoglobin. Here, we used enzyme proximity sequencing (EP-Seq) to measure the peroxidase activity levels of >6,000 human myoglobin variants. The resulting fitness landscape reveals how aromatic substitutions, in particular surface-exposed tryptophans, can enhance peroxidase activity. Using protein language models in tandem with feedforward neural networks, we trained an accurate fitness predictor on the experimental data set and applied it to screen >4 M double mutant variants. The predictions suggested a beneficial role for electron–hole-hopping mutations in improving peroxidase activity. We experimentally tested 20 high-scoring variants in a yeast display assay, all of which outperformed wild-type myoglobin. Three selected variants were also tested in soluble format and similarly showed improved performance. A focused combinatorial library yielded a top double tryptophan variant (Q92W/F107W) with 4.9-fold higher catalytic efficiency than wild type. These results show that deep mutational learning can identify myoglobin variants with enhanced peroxidase activity that are consistent with the involvement of hole-hopping pathways, with broad implications for biocatalyst and redox enzyme design.

Anode‐free concept can fully utilize the unmatched theoretical specific energy of lithium‐metal battery. However, the low stability of the anode interface, including both the morphology of Li metal and the solid electrolyte interphase (SEI), hinders the practical battery implementation and creates safety concerns. In this work, sulfolane‐based localized high‐concentration electrolyte (LHCE) is applied as a sustainable and applicable electrolyte for anode‐free Li‐metal batteries (AFLMBs). The effects of important factors, including type of anode current collector, electrolyte properties, and cycling conditions, are explored in terms of clarifying their impact on the structural and functional properties of LFP‖Cu cells. Flammability tests indicate that the electrolyte is nonflammable by direct ignition under the applied conditions, which is highly beneficial for the safety and sustainability of the AFLMB. The performance of SL‐based LHCE is tested for Li plating–stripping reaction on Cu‐engineered substrates, where the microporous Cu substrates display major improvement, which can be attributed to their enlarged active surface area and open and highly interconnected porous structure. The influence of the key operation parameters, state of charge, depth of discharge, and current density is explored, and useful correlations of these factors with the anode structural properties and battery cycling stability are established.

We present a novel approach to enhance the efficiency and stability of inorganic CsPbI2Br based perovskite solar cells (PSCs) through the incorporation of a solvated palladium (Pd) complex, PdBr2(PhCN)2, into perovskite precursor inks (PhCN = benzonitrile). This modification not only stabilizes the α-phase of CsPbI2Br perovskite owing to Pd2+ ions, which were found to be incorporated into the perovskite structure at the B-site, but also effectively improves the perovskite film morphology through the removal of benzonitrile molecules during annealing. Further systematic study reveals that the addition of PdBr2(PhCN)2 results in a better matched energy-level alignment and reduced charge carrier recombination compared to the unmodified material. As a result, the optimized device enables an efficiency of 16.4% with an open-circuit voltage (VOC) of 1.27V, which outperforms the control device (14.1%, 1.19V). The device with PdBr2(PhCN)2 shows substantially enhanced environmental and operational stabilities, retaining ≈75% and 90% of their initial PCEs after 500h aging, respectively. This study demonstrates the potential of B-site engineering via solvated precursors as an effective route toward stable and efficient inorganic perovskite photovoltaics.

Femtosecond laser processing has emerged as a promising post-deposition method for tailoring the properties of dielectric thin films, offering localized modification without thermal damage. This study investigates the effect of sub-ablative femtosecond laser irradiation on the nonlinear optical response of a TiO2 single-layer coating deposited on soda-lime glass by electron-beam evaporation. The coating was modified using 35 fs pulses at 800 nm delivered at a repetition rate of 1 kHz and a fluence of 0.083 J/cm2 while varying the number of pulses per spot. The effective nonlinear refractive index (n2,eff) and effective nonlinear absorption coefficient (βeff) were measured using the z-scan technique with femtosecond excitation. The as-deposited TiO2 coating exhibited a negative effective nonlinear refractive index, signifying a self-defocusing nonlinear response, while femtosecond laser irradiation leads to pronounced changes in the effective nonlinear parameters. An increase in the magnitude of both effective nonlinear coefficients and a reversal of the sign of the effective nonlinear refractive index are experimentally observed after irradiation with higher pulse numbers. These findings provide experimental evidence that sub-ablative femtosecond laser processing can be used as a post-deposition tool to control the nonlinear optical response of TiO2 thin films.

The present study highlights the HER electrocatalytic performance of PdIrSnZnMo HEA with the delivery of a low overpotential of 17 mV to reach the benchmark current density (−10 mA cm −2 ) and excellent stability for 100 h in an acidic medium.