Doping transition metal in PdSeO_(3)atomic layers by aqueous cation exchange:A new doping protocol for a new 2D photocatalyst

Elemental doping confined in atomically-thin 2 D semiconductors offers a compelling strategy for constructing high performance photocatalysts.Although impressive progress has been achieved based on co-thermolysis method,the choices of dopants as well as semiconductor hosts are still quite limited to yield the elaborate photocatalyst with atomic-layer-confined doping defects,owing to the difficulty in balancing the reaction kinetics of different precursors.This study shows that the cation exchange reaction,which is dictated by the Pearson's hard and soft acids and bases(HSAB)theory and allowed to proceed at mild temperatures,can be developed into a conceptually new protocol for engineering elemental doping confined in semiconductor atomic layers.To this aim,the two atomic layers of a new type of 2 D photocatalyst PdSe0_(3)(PdSe0_(3)2 ALs,1.1 nm)are created by liquid exfoliation and exploited as a proof-of-concept prototype.It is demonstrated that the Mn(Ⅱ)dopants with controlled concentrations can be incorporated into PdSeO_(3)2 ALs via topological Mn^(2+) for-Pd^(2+) cation exchange performed in water/isopropanol solution at 30℃.The resulting Mn-doped PdSeO_(3)2 ALs present enhanced capacity for driving photocatalytic oxidation reactions in comparison with their undoped counterparts.The findings here suggest that the new route mediated by post synthetic cation exchange promises to give access to manifold 2 D confined-doping photocatalysts,with little perturbations on the thickness,morphology,and crystal structure of the atomically-thin semiconductor hosts.

Microreactor platform for continuous synthesis of electronic doped quantum dots

Electronic doped quantum dots(Ed-QDs),by heterovalent cations doping,have held promise for future device concepts in optoelectronic and spin-based technologies due to their broadband Stokes-shifted luminescence,enhanced electrical transport and tailored magnetic behavior.Considering their scale-up requirement and the low yielding of several current colloidal synthesis methods,a stable and efficient bulk synthesis strategy must be developed.Microreactors have long been recognized as an effective platform for producing nanomaterials and fabricating large-scale structures.Here,we chose microreactor platform for continuous synthesis of Ed-QDs in the air at low temperatures.By original reverse cation exchange reaction mechanism together with varying the kinetic conditions of microreactor platform,such as liquid flow rate,the Ag doped CdS(CdS:Ag)Ed-QDs with higher yield have been synthesized successfully due to the continuous synthesis advantages with a high degree of size selectivity.Enabled by microreactor engineering simulation,this research not only provides a new synthetic method towards scale-up production but also enables to improve chemical mass production of similar functional QDs for optical devices,bioimaging and innovative information processing applications.

Electronic structure engineering of single atomic sites by plasmoninduced hot electrons for highly efficient and selective photocatalysis

Single atom(SA)catalysts have achieved great success on highly selective heterogeneous catalysis due to their abundant and homogeneous active sites.The electronic structures of these active sites,restrained by their localized coordination environments,significantly determine their catalytic performances,which are difficult to manipulate.Here,we investigated the effect of localized surface plasmon resonance(LSPR)on engineering the electronic structures of single atomic sites.Typically,core–shell structures consisted of Au core and transition metal SAs loaded N-doped carbon(CN)shell were constructed,namely Au@M-SA/CN(M=Ni,Fe,and Co).It was demonstrated that plasmon-induced hot electrons originated from Au were directionally injected to the M-SAs under visible light irradiation,which significantly changed their electronic structures and meanwhile facilitated improved overall charge separation efficiency.The as-prepared Au@Ni-SA/CN exhibited highly efficient and selective photocatalytic CO_(2) reduction to CO performance,which is 20.8,17.5,and 6.9 times those of Au nanoparticles,Au@CN,and Ni-SA/CN,respectively.Complementary spectroscopy analysis and theoretical calculations confirmed that the plasmon enhanced Ni-SA/CN sites featured increased charge density for efficient intermediate activation,contributing to the superb photocatalytic performance.The work provides a new insight on plasmon and atomic site engineering for efficient and selective catalysis.