Da Wang,Shiwen Dong,Lingsha Wen,Weiting Yu,Zhiqiao He,Qingqing Guo,Xiaohui Lu,Lizhang Wang,Shuang Song,Jun Ma
A metal oxide electrode has been developed for the electrochemical CO 2 reduction reaction (eCO 2 RR). It exhibits superior activity and product selectivity towards eCO 2 RR by circumventing the previously encountered problem of self-reduction with high-valence metals. Specifically, a hydrocerussite [Pb 3 (CO 3 ) 2 (OH) 2 ] thin film has been synthesized in situ on a Pb substrate (denoted as ER-HC) by an electroreduction method using a lead-based metal–organic framework (Pb-MOF) as a precursor. The ER-HC electrode exhibits a high selectivity of 96.8% towards HCOOH production with a partial current density of 1.9 mA cm −2 at −0.88 V vs. the reversible hydrogen electrode (RHE). A higher HCOOH partial current density of 7.3 mA cm −2 has been achieved at −0.98 V vs. RHE. Physicochemical and electrochemical characterization results demonstrate that the defective hydrocerussite surface exhibits appropriate adsorption free energy of formate (HCOO − ) and a lower reaction free energy for HCOOH production from CO 2 , which greatly boosts the eCO 2 RR activity and HCOOH production selectivity. The structure and eCO 2 RR performance of the hydrocerussite thin film remain stable in 0.1 M KHCO 3 as electrolyte, ensuring its durability. Overall, this work not only provides a metal oxide electrode (metal hydroxide, to be more precise) with excellent eCO 2 RR performance, but also expands the in situ electrochemical derivatization strategy for the fabrication of metal oxide electrodes.
Development of new birefringent crystals with enhanced properties remains an ongoing research priority. Through the exploration of guanidinium-containing oxalates with the structural modulation of Pb 2+ and Cl - , a new birefringent crystal, [C(NH 2 ) 3 ]Pb(C 2 O 4 )Cl·H 2 O (GPCCH), was successfully obtained. GPCCH was characterized by two types of π-conjugated building units, which contributes to the coexistence of a wide bandgap of 3.98 eV and a large birefringence of 0.24@546 nm. These findings highlight the synergistic role of π-conjugated building units and partially-chlorinated lead-containing units played in generating fascinating UV birefringent crystals.
Wang Zhao,Jiazheng Zhou,Linan Wang,Wenqi Jin,Yingying Kong,Yu Chu,Junjie Li
Pb-based chalcogenides display abundant structural diversity and distinguished properties. Based on a mixed anion and dimensional reduction combined strategy, a wide band gap Pb-based thiohalide, Pb6Ba3Si2S8I10, has been rationally designed and synthesized experimentally by the flux method. The compound crystallizes in the Rc space group with cell parameters a = 9.7925(2) Å, b = 9.7925(2) Å, and c = 70.628(3) Å and is composed of [SiS4] tetrahedra and unprecedented [PbI5S2] polyhedral units, resulting in a unique quasi-two-dimensional structure, which enriches the chemical and structural diversity of Pb-based thiohalides. The experimental band gap of Pb6Ba3Si2S8I10 was determined to be 2.80 eV. Based on statistical analyses and to the best of our knowledge, it is the largest experimental optical band gap among the known Pb-based thiohalides. The results demonstrate the feasibility of using highly electropositive Ba atoms to regulate the dimensions of the structural framework of thiohalides and give new insights into the structure and property modifications of thiohalides by the mixed anion and dimensional reduction combined strategy.
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