# Promoted hydrogen activation and spillover over Pt/Co3O4 by facet engineering of Co3O4 for enhanced catalytic hydrogenation

## TL;DR

Engineering the crystal facets of Co3O4 enhances hydrogen activation and spillover, boosting catalytic hydrogenation performance.

## Contribution

Tailoring Co3O4 crystal facets modulates Pt nanoparticle electronic structure and hydrogen spillover for improved catalytic activity.

## Key findings

- Pt/Co3O4-o with (111) facets shows highest hydrogenation activity with a TOF of 164.2 h−1.
- Pt/Co3O4-o exhibits stronger H2 activation and weaker nitro group adsorption compared to Pt/Co3O4-c.
- Facet engineering enhances hydrogen spillover and catalytic performance through electronic structure modulation.

## Abstract

The exposed facets of supported metal catalysts play a crucial role in catalytic hydrogenation performance. However, the internal relationship between the support crystal facet and catalytic performance needs to be further explored. Herein, a series of well-defined Pt/Co3O4-x catalysts are fabricated with similar Pt nanoparticle sizes, identical metal loadings, and tailored Co3O4 crystal facets (x = o, t, c; where “o”, “t”, and “c” denote Co3O4 exposing predominantly (111), mixed (111)/(100), and (100) facets, respectively). The electronic structure of Pt nanoparticles and the hydrogen spillover capability of Pt/Co3O4 are modulated by exposing different crystal facets of Co3O4. For the 4-nitrophenol (4-NP) hydrogenation reaction with H2 as the hydrogen source, the Pt/Co3O4-o catalyst with more Pt0 species and stronger hydrogen spillover capability exhibits the best hydrogenation activity with a turnover frequency (TOF) of 164.2 h−1. Mechanistic studies indicate that, compared with Pt/Co3O4-c, the Pt/Co3O4-o exhibits weaker adsorption and activation of the nitro group, while its ability to activate H2 is stronger. The enhanced catalytic activity of Pt/Co3O4-o is attributed to promoted hydrogen activation and spillover. This work highlights support crystal facet engineering for regulating the electronic structure and hydrogen spillover effect, which provides in-depth insight into catalyst design and hydrogenation mechanism.

The (111) facet-induced electron-rich Pt nanoparticles on Co3O4 accelerate both H2 activation and hydrogen spillover dynamics, leading to a superior turnover frequency (TOF) in catalytic hydrogenation.