Mechanistic insight the visible light driven hydrogen generation by plasmonic Au-Cu alloy mounted on TiO2 @B-doped g-C3N4 heterojunction photocatalyst

Abstract

Designing of two dimensional surfaces and interfaces with light-active materials has been established as a versatile approach to increase their photocatalytic activity. In the present work, n-type anatase TiO 2 coupled with p-type B-doped g-C 3 N 4 nanosheet (BCN) were fabricated and Au-Cu nanoalloy with varying atomic ratio were deposited on the p-n heterojunction. The incorporation of Au-Cu on the interface of the dyad enhances light absorption over broad regime, charge separation, and migration. Au-Cu with 1:1 ratio (with an average particle size of 1.2 nm) loaded p-n hetrojunction (TBCAC-1:1) shows excellent photocurrent enhancement (approximately 4.4-folds) in the cathodic direction as compared to their monometallic plasmonic counterpart. Additionally, the catalyst shows photocurrent at zero biased potential as well as lower onset potential as compared to the other alloy. TBCAC-1:1 photocatalyst could able to produce 2150 μmol h −1 g −1 of hydrogen, which is (approximately 3-folds) as compared to their monometallic counterparts. The hydrogen evolution process for Au-Cu (1:1) system was found to be governed by the charge distribution which dictates the binding preference of the Au and Cu sites leading to the water splitting as investigated by DFT calculation. The excellent hydrogen generation by the photocatalyst links to the synergistic effect between Au and Cu associated with the hot electron photochemistry due to surface plasmon resonance phenomenon. Hot electron mediated H 2 generation by a plasmonic TiO 2 /BCN/Au-Cu photocatalyst • n-type TiO 2 with p-type B-doped g-C 3 N 4 nanosheet (BCN) were fabricated and Au-Cu nanoalloy were deposited on it. • Au-Cu on the interface of the dyad enhances light absorption over broad regime, charge separation, and migration. • Au-Cu with 1:1 ratio loaded p-n hetrojunction (TBCAC-1:1) shows excellent photocurrent enhancement in the cathodic direction as compared to other. • TBCAC-1:1 produced 2150 μmol h -1 g -1 of hydrogen (approximately 3-folds) as compared to monometallic counterparts. • The hydrogen evolution process is governed by the charge distribution between Au and Cu sites investigated by DFT calculation.