Bimetallic Pd-In alloy supported on TiO2 nanosheets breaks the rate-limiting step for ultrafast photocatalytic denitrification

Herein, the bimetallic Pd 3 In 1 alloy were deposited onto the crystal facet engineered TiO 2 nanosheet (NS) via one-step photoreduction (Pd 3 In 1 /TiO 2 -NS) for selective conversion of nitrate (NO 3 − ) to N 2 . Bimetallic Pd 3 In 1 provides higher affinity sites to bind NO 3 − and significantly reduces the energy barrier of the rate-limiting step (NO 3 * + e −  → NO 2 *), which is the key for the ultra-fast NO 3 − reduction kinetics. More importantly, the synergistic effect of Pd and In not only suppresses the hydrogen evolution reaction resulting in high efficiency utilization of photogenerated electrons, but also promotes the selective conversion of nitrite (NO 2 − ) to N 2 . Consequently, Pd 3 In 1 /TiO 2 -NS exhibits 100 % NO 3 − conversion and 90 % N 2 selectivity within 20 min in six cycles. One order of magnitude improvement on the NO 3 − reduction kinetic constants of Pd 3 In 1 /TiO 2 -NS (0.254 min −1 ) is achieved compared with pristine TiO 2 -NS and monometallic loaded ones. This work provides new insights into the rational construction of bimetallic alloy cocatalysts for high-efficiency photocatalytic denitrification.