Growth,thermophysical and electrical properties of the nonlinear optical crystal BPO4

Bulk BPO₄ crystals have been successfully grown from high temperature solution of BPO₄, Li₂O, and MoO₃ in the molar ratio of 2.3:1:1.3 by the top‐seeded solution growth (TSSG) method using [101]^c orientation seeds. There are no visible scattering centers and impurity of Mo in the as‐grown BPO₄ crystals, whose optical homogeneity reaches up to 1.6×10^–5/cm. BPO₄ possesses a specific heat of 0.50–1.00 J·g^–1·K^–1 in the temperature range from 298 to 698 K and exhibits strong anisotropic thermal expansion behavior with α_a = 14.2 × 10^–6 K^–1 and α_c = ‐4.0 × 10^–7 K^–1. Moreover, the thermal conductivity coefficients are calculated to be κ_a = 62.4 W·m^–1·K^–1 and κ_c = 51.5 W·m^–1·K^–1, which are remarkably larger than those of some commonly used borates. The measured dielectric constants, ε_a and ε_c, are 4.8 and 6.1, respectively, and the ionic conductivity coefficients, σ_a = 4.3 × 10^–8 S/cm and σ_c = 9.5 × 10^–8 S/cm, are several orders of magnitude lower than that of LiB₃O₅ (LBO). (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Intense d-p Hybridization in Nb3O15 Tripolymer Induced the Largest Second Harmonic Generation Response and Birefringence in Germanates

We herein report two asymmetric germanate crystals, KNbGe₃O₉ and K₃Nb₃Ge₂O₁₃, with different structures and optical properties derived from divergent polymerized forms of GeO₄ and NbO₆ groups. Remarkably, K₃Nb₃Ge₂O₁₃ achieved a rare combination of the strongest second harmonic generation (SHG) response of 17.5×KDP @ 1064 nm and the largest birefringence of 0.196 @ 546 nm in germanates. It features unique [Nb₃O₁₂]_∞ tubular chains constructed by circular Nb₃O₁₅ tripolymers. Theoretical calculations reveal that the d-p interactions in the Nb₃O₁₅ group are responsible for outstanding optical properties. This work emphasizes the significance of the polymerizable functional units in obtaining high-performance nonlinear optical (NLO) crystals.     

Enhancing Local CO2 Adsorption by L-histidine Incorporation for Selective Formate Production Over the Wide Potential Window

Electrochemical carbon dioxide reduction reaction (CO₂RR) to produce valuable chemicals is a promising pathway to alleviate the energy crisis and global warming issues. However, simultaneously achieving high Faradaic efficiency (FE) and current densities of CO₂RR in a wide potential range remains as a huge challenge for practical implements. Herein, we demonstrate that incorporating bismuth-based (BH) catalysts with L-histidine, a common amino acid molecule of proteins, is an effective strategy to overcome the inherent trade-off between the activity and selectivity. Benefiting from the significantly enhanced CO₂ adsorption capability and promoted electron-rich nature by L-histidine integrity, the BH catalyst exhibits excellent FE_formate in the unprecedented wide potential windows (>90 % within −0.1–−1.8 V and >95 % within −0.2–−1.6 V versus reversible hydrogen electrode, RHE). Excellent CO₂RR performance can still be achieved under the low-concentration CO₂ feeding (e.g., 20 vol.%). Besides, an extremely low onset potential of −0.05 V_RHE (close to the theoretical thermodynamic potential of −0.02 V_RHE) was detected by in situ ultraviolet-visible (UV-Vis) measurements, together with stable operation over 50 h with preserved FE_formate of ≈95 % and high partial current density of 326.2 mA cm⁻² at −1.0 V_RHE.