Hydrogen Production Improvement on Water Decomposition Through Internal Interfacial Charge Transfer in M3(PO4)2-M2P2O7 Mixed-Phase Catalyst (M = Co, Ni, and Cu)

Abstract

In this study, three types of Nasicon-type materials, Co 3 (PO 4 ) 2 -CO 2 P 2 O 7 , Ni 3 (PO 4 ) 2 -Ni 2 P 2 O 7 , and Cu 3 (PO 4 ) 2 -Cu 2 P 2 O 7 , were synthesized as mixed-phase catalysts (MPCs) for evaluating their potential as new photocatalytic candidates (called Co 3 (PO 4 ) 2 -CO 2 P 2 O 7 mpc, Ni 3 (PO 4 ) 2 -Ni 2 P 2 O 7 mpc, and Cu 3 (PO 4 ) 2 -Cu 2 P 2 O 7 mpc herein). Based on various physical properties, it was confirmed that there are two phases, M 3 (PO 4 ) 2 and M 2 P 2 O 7 , in which a similar phase equilibrium energy coexists. These colored powders showed UV and visible light responses suitable to our aim of developing 365-nm light-response photocatalysts for overall water-splitting. The photocatalytic performance of Ni 2 (PO 4 ) 3 -Ni 2 P 2 O 7 MPC showed negligible or no activity toward H 2 evolution. However, Co 2 (PO 4 ) 3 -Co 2 P 2 O 7 MPC and Cu 3 (PO 4 ) 2 -Cu 2 P 2 O 7 MPC were determined as interesting materials because of their ability to absorb visible light within a suitable band. Moreover, an internal interface charge transfer was suggested to occur that would lower the recombination rate of electrons and holes. For Cu 3 (PO 4 ) 2 -Cu 2 P 2 O 7 MPC, the charge separation between the electron and hole was advantageously achieved, a water-splitting reaction was promoted, and hydrogen generation was considerably increased. The performance of a catalyst depended on the nature of the active metal added. In addition, the performance of the catalyst was improved when electrons migrated between the inter-phases despite the lack of a heterojunction with other crystals.

A bifunctional Zn/ZrO2–SAPO-34 catalyst for the conversion of syngas to lower olefins induced by metal promoters

“…The binding energy values of the used catalyst were marginally increased compared with the fresh catalyst. 64 For the used catalysts, the lower binding energy values were mainly due to the sulfate species generated on the catalysts surface. 65 3.2 Catalytic activity 3.2.1 Different metal-doped Zn/ZrO 2 -SAPO-34 bifunctional catalysts.…”

Photocatalysis: Activity of Nanomaterials

“…This method proved effective in predicting spectral position of localized plasmonic resonance, a key parameter to design high-efficiency photocatalysts. Kim et al [8] designed three compositions of Nasicon-type materials as mixed-phase catalysts for water splitting. These compositions exhibited enhanced charge separation through inter-phase electron migration.…”