Unexpected Redispersion Effect of Au Nanoclusters for Enormous Enhancement of Electrocatalytic Stability and Activity

Abstract

The irreconcilable conflict between stability and excellent electrocatalytic activity of Au nanoclusters greatly limits their application. Extensive efforts are devoted to fabricating various substrates to immobilize Au nanoclusters while it is still challenging to maintain its electrocatalytic activities for long term tasks due to the highly reactive environments that the Au nanoclusters encounter in electrocatalytic reactions. Herein, an unexpected "redispersion effect" is discovered when Au 25 nanoclusters are loaded on the nanocomposites of black phosphorus and N-doped graphene (AuCs/BP-NG), forming the sandwich configuration with the enhanced stability. The size of Au nanoclusters reduce from 1.56 ± 0.5 to 1.04 ± 0.2 nm, leading to improved catalytic ability. Such redispersion effect yields a super-high electrocatalytic performance of the AuCs/BP-NG toward Cr(VI) sensing that the detection sensitivity achieved 0.414 µA ppb −1 , which is two orders of magnitude higher than the state-of-the-art value. Compared with BP-NG and Au nanoparticles (AuNPs) loaded on BP-NG (AuNPs/BP-NG), the lowest reaction barrier in the rate-determining steps of H 2 CrO 4 reduction is observed. The findings provide an opportunity to develop a superior electrocatalyst in the community of energy and environment-related electrocatalysis.

In Situ Laser-Induced Breakdown Spectroscopy for Chromium Speciation Analysis Based on the Interactions of Oxygen-Containing Groups with Functionalized Co3O4-rGO: Evidence from Advanced Optical Techniques and Density Functional Theoretical Calculations under Electric Field

“…Notably, the ratio of O v to NH 2 –Co 3 O 4 -rGO/HCrO 4 – and COOH–Co 3 O 4 -rGO/Cr­(OH) 2+ decreased from 52.4 to 39.6% and from 43.5 to 37.1%, respectively, revealing that oxygen vacancies might serve as active sites for the adsorption of target ions . In Figure c, the peak position of N 1s moved to the higher energy level after the adsorption of HCrO 4 – by NH 2 –Co 3 O 4 -rGO, and the N–Cr peak emerged in the spectrum of N 1s, demonstrating a significant interaction between N atoms and Cr atoms, reflecting the critical function of amino groups in adsorption of HCrO 4 – . , As shown in Figure d, the 2p 3/2 orbital energy of Co atoms in NH 2 –Co 3 O 4 -rGO/HCrO 4 – and COOH–Co 3 O 4 -rGO/Cr­(OH) 2+ shifted 0.38 and 0.33 eV to the high energy level, respectively. Moreover, the valence cycle of Co­(II)/(III) has been verified, since the ratio of Co­(II) in NH 2 –Co 3 O 4 -rGO and COOH–Co 3 O 4 -rGO after adsorption decreased from 23.19 to 18.44% and from 25.39 to 17.40%, the ratio of Co­(III) in NH 2 –Co 3 O 4 -rGO/HCrO 4 – and COOH–Co 3 O 4 -rGO/Cr­(OH) 2+ increased from 47.37 to 58.89% and from 49.60 to 55.49%, indicating that Co 3 O 4 nanoparticles may act as the effective active sites for the target ions .…”

“…− by NH 2 −Co 3 O 4 -rGO, and the N−Cr peak emerged in the spectrum of N 1s, demonstrating a significant interaction between N atoms and Cr atoms, reflecting the critical function of amino groups in adsorption of HCrO 4 − . 36,37 As shown in Figure 7d − and COOH−Co 3 O 4 -rGO/Cr(OH) 2+ increased from 47.37 to 58.89% and from 49.60 to 55.49%, indicating that Co 3 O 4 nanoparticles may act as the effective active sites for the target ions. 38 The obvious shift of binding energy for Cr 2p could be observed in Figure 7e after the adsorption of HCrO 4 − and Cr(OH) 2+ , confirming that Cr atoms received electrons during the adsorption process.…”

Modulating paired Ir–O–Ir via electronic perturbations of correlated Ir single atoms to overcome catalytic selectivity

“…S9 † ). 50 Details regarding the TOF calculation are shown in the ESI. † In short, Ir SAs/Co 3 O 4 /GCE exhibited the highest activity with an efficiency of 4.47 nm −2 s −1 , which was almost 20-fold and 10-fold better than Co 3 O 4 /GCE (0.45 nm −2 s −1 ) and IrO 2 /Co 3 O 4 /GCE (0.27 nm −2 s −1 ), respectively, which demonstrated the prominent catalytic activity of Ir SAs/Co 3 O 4 /GCE for the electroanalysis of As( iii ).…”