Single-doped charged gold cluster with highly selective catalytic activity for the reduction of SO2 by CO: First-principles study

It is important for environmental protection to search for catalysts with excellent performance and cost-effective to reduce SO2 by CO. In this work, using first-principles calculation, we have studied the catalytic performance of Au5Mn（M = Ni, Pd, Pt, Cu, Ag, Au; n = 1, 0,-1） clusters, and showed that, by giving a negative charge to the Au5M（M = Cu,Ag, Au, Pd） clusters, we could improve the selectivity of SO2 and avoid effectively catalyst CO poisoning simultaneously.At the same time, the catalytic reaction rate for the reduction of SO2 by CO with Au5M-（M = Cu, Ag, Au, Pd） clusters is greatly improved when the Au5M clusters are charged. These advantages can be well explained by the charge transfer between the clusters and adsorbed molecules, which means that we can effectively control the performance of the catalyst.The equilibrium structures of Au5Mn（M = Ni, Pd, Pt, Cu, Ag, Au; n = 1, 0,-1） clusters without or with adsorbed SO2 or CO molecule are also discussed, and the most stable geometrical structures of Aun5 M-ML（ML = SO2, CO, SO, and COS）can be explained very well by the match of orbitals symmetry and density of electron cloud through their frontier molecular orbitals. Considering the catalyst cost（Cu is much cheaper than Ag and Au）, selectivity of SO2, and effectively avoiding the catalyst CO poisoning, we propose that Au5Cu-is an ideal catalyst for getting rid of SO2 and CO simultaneously.

Transition metal anchored on C_(9)N_(4) as a single-atom catalyst for CO_(2) hydrogenation: A first-principles study

To alleviate the greenhouse effect and maintain the sustainable development, it is of great significance to find an efficient and low-cost catalyst to reduce carbon dioxide(CO_(2)) and generate formic acid(FA). In this work, based on the first-principles calculation, the catalytic performance of a single transition metal(TM)(TM = Cr, Mn, Fe, Co, Ni, Cu, Zn,Ru, Rh, Pd, Ag, Cd, Ir, Pt, Au, or Hg) atom anchored on C_(9)N_(4) monolayer(TM@C_(9)N_(4)) for the hydrogenation of CO_(2) to FA is calculated. The results show that single TM atom doping in C_(9)N_(4) can form a stable TM@C_(9)N_(4) structure, and Cu@C_(9)N_(4) and Co@C_(9)N_(4) show better catalytic performance in the process of CO_(2) hydrogenation to FA(the corresponding maximum energy barriers are 0.41 eV and 0.43 e V, respectively). The partial density of states(PDOS), projected crystal orbital Hamilton population(p COHP), difference charge density analysis and Bader charge analysis demonstrate that the TM atom plays an important role in the reaction. The strong interaction between the 3d orbitals of the TM atom and the non-bonding orbitals(1πg) of CO_(2) allows the reaction to proceed under mild conditions. In general, our results show that Cu@C_(9)N_(4) and Co@C_(9)N_(4) are a promising single-atom catalyst and can be used as the non-precious metals electrocatalyst for CO_(2) hydrogenation to formic acid.

Single boron atom anchored on graphitic carbon nitride nanosheet(B/g-C_(2)N)as a photocatalyst for nitrogen fixation:A first-principles study

It is essential to explore high efficient catalysts for nitrogen reduction in ammonia production.Based on the first-principles calculation,we find that B/g-C_(2)N can serve as high performance photocatalyst in N_(2)fixation,where single boron atom is anchored on the g-C_(2)N to form B/g-C_(2)N.With the introduction of B atom to g-C_(2)N,the energy gap reduces from 2.45 eV to 1.21 eV and shows strong absorption in the visible light region.In addition,N_(2)can be efficiently reduced on B/g-C_(2)N through the enzymatic mechanism with low onset potential of 0.07 V and rate-determining barrier of 0.50 eV.The"acceptance-donation"interaction between B/g-C_(2)N and N_(2)plays a key role to active N_(2),and the BN_(2)moiety of B/g-C_(2)N acts as active and transportation center.The activity originates from the strong interaction between 1π1π*orbitals of N_(2)and molecular orbitals of B/g-C_(2)N,the ionization of 1πorbital and the filling of 1π*orbital can increase the N≡N bond length greatly,making the activation of N_(2).Overall,this work demonstrates that B/g-C_(2)N is a promising photocatalyst for N_(2)fixation.

Moisture stable and ultrahigh-rate Ni/Mn-based sodium-ion battery cathodes via K^(+)decoration

As one of the most promising cathodes for sodium-ion batteries(SIBs),the layered transition metal oxides have attracted great attentions due to their high specific capacities and facile synthesis.However,their applications are still hindered by the problems of poor moisture stability and sluggish Na^(+)diffusion caused by intrinsic structural Jahn–Teller distortion.Herein,we demonstrate a new approach to settle the above issues through introducing K^(+)into the structures of Ni/Mn-based materials.The physicochemical characterizations reveal that K^(+)induces atomic surface reorganization to form the birnessite-type K_(2)Mn_(4)O_(8).Combining with the phosphate,the mixed coating layer protects the cathodes from moisture and hinders metal dissolution into the electrolyte effectively.Simultaneously,K^(+)substitution at Na site in the bulk structure can not only widen the lattice-spacing for favoring Na^(+)diffusion,but also work as the rivet to restrain the grain crack upon cycling.The as achieved K^(+)-decorated P2-Na_(0.67)Mn_(0.75)Ni_(0.2)5O_(2)(NKMNO@KM/KP)cathodes are tested in both coin cell and pouch cell configurations using Na metal or hard carbon(HC)as anodes.Impressively,the NKMNO@KM/KP||Na half-cell demonstrates a high rate performance of 50 C and outstanding cycling performance of 90.1%capacity retention after 100 cycles at 5 C.Furthermore,the NKMNO@KM/KP||HC fullcell performed a promising energy density of 213.9 Wh·kg^(−1).This performance significantly outperforms most reported state-ofthe-art values.Additionally,by adopting this strategy on O3-NaMn_(0.5)Ni_(0.5)O_(2),we further proved the universality of this method on layered cathodes for SIBs.