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Wen-Li Xie, Zhen-Dong Sun. Hydrogen Generation from Water Splitting by Catalysts of Platinum-Based Clusters Pt3X (X=Al, Si, Cu) and CO Oxidation by Their By-Product[J]. Chinese Journal of Chemical Physics , 2020, 33(1): 58-64. doi: 10.1063/1674-0068/cjcp1910190
Citation: Wen-Li Xie, Zhen-Dong Sun. Hydrogen Generation from Water Splitting by Catalysts of Platinum-Based Clusters Pt3X (X=Al, Si, Cu) and CO Oxidation by Their By-Product[J]. Chinese Journal of Chemical Physics , 2020, 33(1): 58-64. doi: 10.1063/1674-0068/cjcp1910190

Hydrogen Generation from Water Splitting by Catalysts of Platinum-Based Clusters Pt3X (X=Al, Si, Cu) and CO Oxidation by Their By-Product

doi: 10.1063/1674-0068/cjcp1910190
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  • Corresponding author: Zhen-Dong Sun, E-mail: zdsun@sdu.edu.cn
  • Part of the special topic on "The 3rd Asian Workshop on Molecular Spectroscopy"
  • Received Date: 2019-10-31
  • Accepted Date: 2019-12-12
  • Publish Date: 2020-02-27
  • Reducing sizes of precious metals and utilization of the mixed small clusters of them as catalysts in reactions are important methods due to more active sites for higher catalytic efficiency. Based on first-principles calculations in this work, we found that the platinum-based clusters of Pt$ _3 $X (X = Al, Si, Cu) which have the magic number 4 can effectively catalyze the water decomposition and hydrogen production in just one-step reaction process. The adsorbates of the H$ _2 $O@Pt$ _3 $X clusters have strong absorption in the ultraviolet and visible regions with wavelength from 300 nm to 760 nm, indicating the sunlight can be used to drive catalytic hydrolysis for producing clean hydrogen. In addition, the O atom remains on the clusters after hydrolysis and can react with CO to form CO$ _2 $ in activation barrier of 0.34$ - $0.58 eV, showing the recycling ability of the products after hydrolysis for eliminating the "poisoning'' CO by oxidation. Moreover, the formed CO$ _2 $ molecule can be detached from the Pt$ _3 $X clusters at 323 K. Our results provide interesting guidance for practical designing the useful photocatalysts.
  • Part of the special topic on "The 3rd Asian Workshop on Molecular Spectroscopy"
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    [12] R. T. Fryer and R. J. Lad, J. Alloy. Compd. 682, 216 (2016). doi:  10.1016/j.jallcom.2016.04.260
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    [14] M. J. Frisch, G. W. Trucks, H. B. Schlegel, G. E. Scuseria, M. A. Robb, J. R. Cheeseman, G. Scalmani, V. Barone, B. Mennucci, G. A. Petersson, H. Nakatsuji, M. Caricato, X. Li, H. P. Hratchian, A. F. Izmaylov, J. Bloino, G. Zheng, J. L. Sonnenberg, M. Hada, M. Ehara, K. Toyota, R. Fukuda, J. Hasegawa, M. Ishida, T. Nakajima, Y. Honda, O. Kitao, H. Nakai, T. Vreven, J. A. Montgomery, Jr., J. E. Peralta, F. Ogliaro, M. Bearpark, J. J. Heyd, E. Brothers, K. N. Kudin, V. N. Staroverov, R. Kobayashi, J. Normand, K. Raghavachari, A. Rendell, J. C. Burant, S. S. Iyengar, J. Tomasi, M. Cossi, N. Rega, J. M. Millam, M. Klene, J. E. Knox, J. B. Cross, V. Bakken, C. Adamo, J. Jaramillo, R. Gomperts, R. E. Stratmann, O. Yazyev, A. J. Austin, R. Cammi, C. Pomelli, J. W. Ochterski, R. L. Martin, K. Morokuma, V. G. Zakrzewski, G. A. Voth, P. Salvador, J. J. Dannenberg, S. Dapprich, A. D. Daniels, O. Farkas, J. B. Foresman, ¨ J. V. Ortiz, J. Cioslowski, and D. J. Fox, Gaussian 09, Revision A. 02, Wallingford, 200. CT: Gaussian. Inc., (2009).
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Hydrogen Generation from Water Splitting by Catalysts of Platinum-Based Clusters Pt3X (X=Al, Si, Cu) and CO Oxidation by Their By-Product

doi: 10.1063/1674-0068/cjcp1910190

Abstract: Reducing sizes of precious metals and utilization of the mixed small clusters of them as catalysts in reactions are important methods due to more active sites for higher catalytic efficiency. Based on first-principles calculations in this work, we found that the platinum-based clusters of Pt$ _3 $X (X = Al, Si, Cu) which have the magic number 4 can effectively catalyze the water decomposition and hydrogen production in just one-step reaction process. The adsorbates of the H$ _2 $O@Pt$ _3 $X clusters have strong absorption in the ultraviolet and visible regions with wavelength from 300 nm to 760 nm, indicating the sunlight can be used to drive catalytic hydrolysis for producing clean hydrogen. In addition, the O atom remains on the clusters after hydrolysis and can react with CO to form CO$ _2 $ in activation barrier of 0.34$ - $0.58 eV, showing the recycling ability of the products after hydrolysis for eliminating the "poisoning'' CO by oxidation. Moreover, the formed CO$ _2 $ molecule can be detached from the Pt$ _3 $X clusters at 323 K. Our results provide interesting guidance for practical designing the useful photocatalysts.

Part of the special topic on "The 3rd Asian Workshop on Molecular Spectroscopy"
Wen-Li Xie, Zhen-Dong Sun. Hydrogen Generation from Water Splitting by Catalysts of Platinum-Based Clusters Pt3X (X=Al, Si, Cu) and CO Oxidation by Their By-Product[J]. Chinese Journal of Chemical Physics , 2020, 33(1): 58-64. doi: 10.1063/1674-0068/cjcp1910190
Citation: Wen-Li Xie, Zhen-Dong Sun. Hydrogen Generation from Water Splitting by Catalysts of Platinum-Based Clusters Pt3X (X=Al, Si, Cu) and CO Oxidation by Their By-Product[J]. Chinese Journal of Chemical Physics , 2020, 33(1): 58-64. doi: 10.1063/1674-0068/cjcp1910190
  • Hydrogen is an ideal sustainable energy source for our society. Platinum (Pt) metals are known to be effective catalysts for catalytic hydrolysis to hydrogen production due to their unique and excellent catalytic properties [1-5], especially when they are used together with the inexhaustible energy of sunlight in stimulating the reaction for water (H$ _2 $O) splitting [6]. However, the low reserve and high cost of these bulk precious metals largely limit their wide applications. On the other hand, reducing the sizes of precious metals to the cluster scale is an effective way in designing a cost-effective catalyst due to the number of reactive sites and thereby the catalytic activity can be increased [7].

    The Pt$ _4 $ cluster has a stable tetrahedral structure, which can maximize its efficiency by utilizing almost all platinum atoms to effectively extract H$ _2 $ from the H$ _2 $O molecule in a two-step reaction [8, 9]. In this work, we are interested in a one-step reaction using a binary platinum-based alloy Pt$ _3 $X as a catalyst which is formed by adding a second low-cost element X (hereafter X = Al, Si, Cu) to the platinum and has the occurrence of the same magic number 4 as the Pt$ _4 $ cluster. Wen et al. have studied the geometrical structures and magnetic properties of the neutral and charged Pt$ _3 $Al clusters using density functional theory methods [10]. The neutral Pt$ _3 $Al cluster can be obtained by replacing one Pt atom with Al atom in Pt$ _4 $ cluster and has a stable structure of tetrahedron. Rather than a new catalyst for photocatalytic water splitting as studied in this work, the Pt$ _3 $Cu alloy nanoparticle can be prepared as highly active electrocatalysts for oxygen reduction reaction in acidic and alkaline electrolyte solutions. The introduction of Cu reduces the "poisoning effect'' associated with the important electrolyte components of proton exchange membrane fuel cells [11]. Recently, Fryer and Lad reported the synthesis and thermal stability of Pt$ _3 $Si film grown by E-beam co-evaporation method [12]. Here, the advantages of thermodynamics easily attainable for the Pt$ _3 $Si cluster are fully used as an alternatively cheap catalyst for generation of hydrogen from the hydrolysis reaction. We found that the non-metallic atom Si and three Pt atoms in the Pt$ _3 $Si cluster all are active sites, the activation energy in a one-step reaction driven by the solar energy is lower in the Pt$ _3 $Si cluster than those in the Pt$ _3 $Al and Pt$ _3 $Cu clusters, and the products of the Pt$ _3 $X clusters after hydrolysis can be reused to eliminate the "poisoning'' CO molecule by oxidation into CO$ _2 $ molecule.

  • We have carried out the structural calculations by a gradient-corrected hybrid density function theory (DFT) method [13] using the Gaussian 09 software program package [14]. The B3LYP method with the basis sets of Los Alamos National Laboratory 2-Double-Z (LANL2DZ) was utilized. The absorption coefficient on the wavelength of the exciting light was calculated by a multifunctional program for wavefunction analysis (Multiwfn) [15].

    We have optimized the geometry structures of the Pt$ _3 $X clusters to obtain the stable ones by carrying out the global energy minimization on the potential energy surface, and then considered the possible adsorption sites, including the top, bridge, and hollow sites, for H$ _2 $O molecule on the Pt$ _3 $X clusters. The visualization software GaussView 6.0 was used to construct the transition states (TS) between the reactants (R) and products (P). Frequency calculations were performed for characterizing the stable geometry structures of the reactants and products with no imaginary frequencies and those in transition states with only one imaginary frequency, respectively. The intrinsic reactions coordinate (IRC) presentations were then calculated and used to track the minimum energy paths, probe the reaction paths, and confirm proper locations of these intermediate states.

    The adsorption energy $ E_{\rm{a}} $, activation energy $ E_{\rm{act}} $, and enthalpy of reactions $ E_{\rm{r}} $ were discussed to identify the preferable reactions in generating H$ _2 $. They are calculated respectively by

    Where $ E $(H$ _2 $O@Pt$ _3 $X) is the total energy of the stable H$ _2 $O@Pt$ _3 $X cluster. $ E $(H$ _2 $O) and $ E $(Pt$ _3 $X) refer to the total energy of reactants of the H$ _2 $O molecule and the Pt$ _3 $X cluster, respectively. $ E $(TS) is the total energy of one product of the cluster in a transition state. $ E $(2H@(O+Pt$ _3 $X)) is the total energy of two H atoms to the Pt$ _3 $X cluster adsorbed by one O atom. The calculated Hessian values at temperature of 298.15 K and pressure of 1 bar were used to estimate the thermal corrections of the standard enthalpies and free energy. In order to show the motions of the generated CO$ _2 $ molecule from the Pt$ _3 $X clusters at suitable temperature, the atom centered density matrix propagation at 323 K [16-18] was used and molecular dynamics simulation was performed at a time step of 0.1 fs in simulation time of 0.1 ps.

  • To obtain the most stable structures of the Pt$ _3 $X clusters and understand their abilities for absorption of the H$ _2 $O molecule, as shown in FIG. 1, the optimized geometric structures and the maps of the surface electrostatic potential (SEP) of the H$ _2 $O molecule and Pt$ _3 $X clusters are studied. Table Ⅰ lists the bond length between two atoms and the angle between two bonds of the stable Pt$ _3 $X cluster, which are found to be slightly different from those of the Pt$ _4 $ cluster in tetrahedron [19].

    Table Ⅰ.  Bond length and bong angle of the stable Pt$ _3 $X clusters

    Figure 1.  (A) Optimized geometric structures, (B) isosurface maps, and (C) contour maps of surface electrostatic potential of the H$ _2 $O molecule and Pt$ _3 $X clusters

    The positive region in blue of the SEP corresponds to the electrophilic reactivity by offering adsorption sites for the H$ _2 $O molecule. As can be seen from the isosurface map and confirmed by the contour map of SEP, the Pt and Cu atoms have more blue regions than Si atom and Al atom. The more charges transfer from O to atoms in the Pt$ _3 $X clusters, the more work function reduce for the latter, and the less activation energies are required for H$ _2 $O dissociation on the Pt$ _3 $X clusters.

    We carefully examined the adsorptions of the H$ _2 $O molecule on atop, bridge, and face sites of the Pt$ _3 $X clusters after tedious optimizations and frequencies analyses. We found that the H$ _2 $O molecule is adsorbed on atop sites of three Pt$ _3 $X clusters. As shown in FIG. 2(a) , (b), and (c) for X = Al, Si, and Cu, respectively, the O atom of H$ _2 $O is adsorbed to the X atom of the Pt$ _3 $X clusters in complex R$ _4 $, and to No.1, 2, and 3 of the Pt atom of the Pt$ _3 $X clusters in complex R$ _1 $, R$ _2 $, and R$ _3 $, respectively. The stable structures of them, together with the corresponded adsorption energy $ E_{\rm{a}} $ calculated by Eq.(1), are shown in FIG. 2. From the adsorption energy $ E_{\rm{a}} $, one can see that the H$ _2 $O molecule is more likely adsorbed to the Cu atom and Pt atoms than the Si atom and Al atom, which are confirmed by the energy gaps analyzed in terms of the molecular orbitals (MOs) shown in FIG. 3.

    Figure 2.  Stable structures and adsorption energies of the H$ _2 $O@Pt$ _3 $X clusters. (a) X = Al, (b) X = Si, and (c) X = Cu.

    Figure 3.  The energy of LUMO of H$ _2 $O and HOMO of Pt$ _3 $X. MOs are rendered at 0.02 isovalues

    FIG. 3 shows energy of the highest occupied molecular orbital (HOMO) of the Pt$ _3 $X clusters and the lowest unoccupied molecular orbital (LUMO) of the H$ _2 $O molecule in considering transformations of electrons from the H$ _2 $O to Pt$ _3 $X clusters in adsorption process. The smaller energy gap indicates that the Pt$ _3 $Cu cluster is more favorable than the Pt$ _3 $Al and Pt$ _3 $Si cluster for the adsorption and dissociation of the H$ _2 $O molecule.

  • The dissociation of the adsorbed H$ _2 $O molecule from the Pt$ _3 $X clusters was studied by adjusting the length of the O$ - $H bond and the angle of H$ - $O$ - $H of the reactants in transition states. The geometrical structures of these reactants were optimized and confirmed with just one virtual frequency, and were further used to track the reaction paths in calculations of the IRC presentations. FIG. 4 shows the reaction paths of H$ _2 $O+Pt$ _3 $X$ \rightarrow $2H@(O+Pt$ _3 $X) with atom X as Al, Si, and Cu. In FIG. 4, the energy of the initial reactants is set to zero. For cluster structures in the initial, intermediate, and final state in one reaction process, they are marked by square and their corresponding activation energy $ E_{\rm{act}} $ and enthalpy of reactions $ E_{\rm{r}} $ are written by the same color.

    Figure 4.  Reaction paths of H$ _2 $O+Pt$ _3 $X$ \rightarrow $2H@(O+Pt$ _3 $X) with atom X as (a) Al, (b) Si, and (c) Cu

    The results in FIG. 4 show that just one-step reaction can produce two H atoms from the initial reactants, three products for X = Al and Cu atoms and four products for X = Si atom can be generated. Pt atoms of the Pt$ _3 $Al and Pt$ _3 $Cu clusters are active sites and all four atoms of Pt$ _3 $Si are active sites in water dissociation. For X = Al, Si, and Cu, the activation energies of their three products (P$ _1 $, P$ _2 $, and P$ _3 $) are around their average value of about 3.79, 3.67, and 3.60 eV, respectively, which are larger than the activation energy 3.05 eV of the forth product P$ _4 $ for X = Si. The enthalpy of reactions is about from 2.0 eV to 3.2 eV, however, it is 0.22 eV for the product P$ _4 $ of the Pt$ _3 $Si cluster, indicating much stronger attractions between Si and Pt atoms in the product P$ _4 $ than that in products P$ _1 $, P$ _2 $, and P$ _3 $ of the Pt$ _3 $Si cluster. Rather than by a one-step reaction path described here and shown in FIG. 4 for the Pt$ _3 $X clusters, two H atoms can also be produced by a two-step reaction path with the dissociation of H$ _2 $O molecule adsorbed on Pt atom of the Pt$ _4 $ clusters [8]. Obviously, it has a higher priority to the Pt$ _3 $X clusters studied in this work than the Pt$ _4 $ clusters as catalyzers in hydrolysis in hydrogen generations.

    Population analyses of Mulliken charges of clusters in TS and Pt$ _3 $X, H$ _2 $O, H$ _2 $O@Pt$ _3 $X, and H$ _2 $@(O+Pt$ _3 $X) in H$ _2 $O dissociation processes of reactants (R), clusters in transition states (TS), and products (P) are calculated for understanding and thereby conforming the hydrolysis processes in the above mentioned reaction paths. FIG. 5 shows variations of Mulliken charges of the Pt$ _3 $X clusters in state of R$ _1 $, TS$ _1 $, and P$ _1 $ shown in FIG. 4. In addition, the cases for state of R$ _4 $, TS$ _4 $, and P$ _4 $ of the Pt$ _3 $Si cluster are also shown in the second last row in FIG. 5 for emphasizing the similar action to metal atoms by the non-metal atom of Si. Each atom in various states in FIG. 5 has its number and the Mulliken charges in decimal. The total pure Mulliken charge is zero for the H$ _2 $O molecule and the Pt$ _3 $X clusters shown in the first column in FIG. 5. From changes of the Mulliken charges of atoms in the clusters during the processes of R$ _1 $$ \rightarrow $TS$ _1 $$ \rightarrow $P$ _1 $ and R$ _4 $$ \rightarrow $TS$ _4 $$ \rightarrow $P$ _4 $, one can clearly see that electron transfers among bonded atoms cause decreases of the charges of the O and two H atoms. This causes deductions of the electrostatic attractions between O atom and two H atoms, and thereby the gradual dissociations of two H atoms from the adsorbed H$ _2 $O on the Pt$ _3 $X clusters. The structures of the clusters in FIG. 5 are consistent well with those in the reaction paths shown in FIG. 4.

    Figure 5.  Mulliken charge distribution variations of the Pt$ _3 $X, H$ _2 $O@Pt$ _3 $X, and H$ _2 $@(O+Pt$ _3 $X) clusters in the H$ _2 $O dissociation processes of reactants (R), clusters in transition states (TS), and products (P). The connections between O and Pt atoms are not shown in the H$ _2 $O@Pt$ _3 $X clusters

    When two H atoms are dissociated, we found that the bond length between them reaches 0.75 Å, which closes to the bond length of the H$ _2 $ molecule. The bond length between two H atoms and O atom is 2.65 Å and the total charge of two H atoms is non-zero. The averaged adsorption energy of the products of 2H@(O+Pt$ _3 $X) for X = Al, Si, and Cu atom is calculated to be about $ - $0.04 eV, which also indicates that two H atoms will be freed from the bond of the O+Pt$ _3 $X clusters and form the H$ _2 $ molecule at room temperature.

    In order to know if the energy of sunlight can be used to drive water dissociation by catalysts of the Pt$ _3 $X clusters, we calculated the dependence of absorption coefficient on the wavelength of the exciting radiation for three reactants of the H$ _2 $O@Pt$ _3 $X clusters with the structure of R$ _1 $, which are shown in FIG. 6. We found that the H$ _2 $O@Pt$ _3 $Al and H$ _2 $O@Pt$ _3 $Cu clusters have strong absorptions in the visible range from 400 nm to 760 nm. The H$ _2 $O@Pt$ _3 $Si cluster has the highest absorption coefficient in the H$ _2 $O@Pt$ _3 $X clusters, and the absorption peak is at ultraviolet wavelength of 320 nm. These results suggest that the Pt$ _3 $X clusters are useful photocatalysts driven by the sunlight for catalytic hydrolysis.

    Figure 6.  Dependence of absorption coefficient on the wavelength of the exciting radiation for three reactants of the H$ _2 $O@Pt$ _3 $X clusters with the structure of R$ _1 $. Atom X is (a) Al, (b) Si, and (c) Cu

  • After the hydrolyzed products of the O+Pt$ _3 $X clusters were optimized, we obtained their stable structures with no virtual frequency appearing. We found that CO can seize the Pt atom of the O+Pt$ _3 $X clusters and be oxidized to form CO$ _2 $ over one low energy barrier. We show in FIG. 7 the stable structures of O+Pt$ _3 $X, reactant of CO@(O+Pt$ _3 $X), cluster in TS (transition state), and the product of CO$ _2 $@Pt$ _3 $X. In FIG. 7, the symbols of O+Pt$ _3 $Al (P$ _1' $) and O+Pt$ _3 $Si (P$ _4' $) refer to the product of the O+Pt$ _3 $Al and O+Pt$ _3 $Si cluster, respectively. O atom connects to Pt atom (No.1) for the former and to the Si atom (No.4) for the latter.

    Figure 7.  Stable structures of O+Pt$ _3 $X, CO@(O+Pt$ _3 $X), cluster in transition state (TS), and CO$ _2 $@Pt$ _3 $X

    FIG. 8 shows the reaction paths by the IRC presentations of CO@(O+Pt$ _3 $X)$ \rightarrow $CO$ _2 $@Pt$ _3 $X with atom X as Al (a), Si (b), and Cu (c). As described above for FIG. 4, for cluster structures in the initial, intermediate, and final state in one reaction process, they are marked by square and their corresponding activation energy $ E_{\rm{act}} $ and enthalpy of reactions $ E_{\rm{r}} $ are written by the same color.

    Figure 8.  Reaction paths of CO@(O+Pt$ _3 $X)$ \rightarrow $CO$ _2 $@Pt$ _3 $X with atom X as (a) Al, (b) Si, and (c) Cu. The energy of the initial reactants is set to zero

    We found that the energy barrier of Si atom (0.58 eV) is different from that of Pt atom, which is higher than others. The enthalpy of reaction is 0.34 eV, which is endothermic reaction. As shown in Table Ⅱ, the adsorption energy of the CO$ _2 $ molecule adsorbed on Pt atom of Pt$ _3 $X is from $ - $0.41 to $ - $0.99 eV. It is 1.02 eV when the CO$ _2 $ molecule is adsorbed on Si atom of Pt$ _3 $Si. The distance between C atom of CO$ _2 $ and Pt atom or between C atom of CO$ _2 $ and Si atom in the adsorption sites of Pt$ _3 $X is in the range of 1.88$ - $2.07 Å.

    Table Ⅱ.  Adsorption energy $ E_{\rm{a}} $ (in eV) of CO$ _2 $ adsorbed on Pt$ _3 $X cluster

    To illustrate the CO$ _2 $ molecule releasing from the Pt$ _3 $X clusters at a certain temperature higher than 293.15 K, we performed the molecular dynamics simulations at 323 K on the CO$ _2 $@Pt$ _3 $X clusters using the atom centered density matrix propagation model. We show the distance $ D_{\rm{c}} $ between geometric centers of the CO$ _2 $ molecule and that of the 1-Pt$ _3 $Al, 4-Pt$ _3 $Si, and 1-Pt$ _3 $Cu clusters, respectively, vs. simulation step ($ \times $ 0.1 fs) in FIG. 9. Molecular dynamics simulation was performed at a time step of 0.1 fs in a simulation time of 0.1 ps. From FIG. 9, we know that the CO$ _2 $ molecule gradually gets away from the Pt$ _3 $X clusters. The centroid distance between the CO$ _2 $ molecule and the Pt$ _3 $X cluster increases with time. It varies from 2.06 Å to 3.75 Å, from 3.44 Å to 4.35 Å, and from 3.02 Å to 4.69 Å for X = Al, Si, and Cu, respectively. Namely, the CO$ _2 $ molecule escapes from Pt$ _3 $X cluster at 323 K.

    Figure 9.  Distance $ D_{\rm{c}} $ (in Å) between geometric centers of the CO$ _2 $ molecule and that of the 1-Pt$ _3 $Al, 4-Pt$ _3 $Si, and 1-Pt$ _3 $Cu cluster, respectively, vs. simulation step ($ \times $0.1 fs)

  • Reactions of the Pt$ _3 $X (X = Al, Si, Cu) cluster with the H$ _2 $O molecule and the hydrolyzed product of O+Pt$ _3 $X with the CO molecule have been studied using the first principle calculations. All structures of the potential energy surfaces are determined and characterized at the DFT-B3LYP level. The dopant Al, Si, and Cu atoms are responsible for the increase of the ability of the Pt$ _3 $X clusters to capture H$ _2 $O. The IRC presentations of H$ _2 $O dissociation on the Pt$ _3 $X clusters show that all the locations of Pt and Si atoms of the Pt$ _3 $X clusters can split H$ _2 $O into two H atoms and form H$ _2 $ by only one step reaction with 3.58$ - $3.85 eV that can be provided by solar energy. The results of IRC calculations also show that the "poisoning'' CO molecule can seize O atom of the product O+Pt$ _3 $X produced from the hydrolysis reaction to generate CO$ _2 $ via lower energy barrier of 0.34$ - $0.58 eV. Molecular dynamics simulation on the product of CO$ _2 $@Pt$ _3 $X at 323 K shows that the CO$ _2 $ molecule gets rid of the Pt$ _3 $X clusters and becomes a free CO$ _2 $ molecule, showing the recycling ability of the products after hydrolysis for elimination the "poisoning'' CO by oxidation. Our results provide interesting guidance for practically designing the useful photocatalysts.

  • This work was supported by the National Natural Science Foundation of China (No.91536105, No.11174186, and No.11074147) and the Tianshan Scholar Program.

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