Cooperative Rh-O₅/Ni(Fe) Site for Efficient Biomass Upgrading Coupled with H₂ Production

Abstract

Designing efficient and durable bifunctional catalysts for 5-hydroxymethylfurfural (HMF) oxidation reaction (HMFOR) and hydrogen evolution reaction (HER) is desirable for the co-production of biomass-upgraded chemicals and sustainable hydrogen, which is limited by the competitive adsorption of hydroxyl species (OHads) and HMF molecules. Here, we report a class of Rh–O5/Ni­(Fe) atomic site on nanoporous mesh-type layered double hydroxides with atomic-scale cooperative adsorption centers for highly active and stable alkaline HMFOR and HER catalysis. A low cell voltage of 1.48 V is required to achieve 100 mA cm–2 in an integrated electrolysis system along with excellent stability (>100 h). Operando infrared and X-ray absorption spectroscopic probes unveil that HMF molecules are selectively adsorbed and activated over the single-atom Rh sites and oxidized by in situ-formed electrophilic OHads species on neighboring Ni sites. Theoretical studies further demonstrate that the strong d–d orbital coupling interactions between atomic-level Rh and surrounding Ni atoms in the special Rh–O5/Ni­(Fe) structure can greatly facilitate surface electronic exchange-and-transfer capabilities with the adsorbates (OHads and HMF molecules) and intermediates for efficient HMFOR and HER. We also reveal that the Fe sites in Rh–O5/Ni­(Fe) structure can promote the electrocatalytic stability of the catalyst. Our findings provide new insights into catalyst design for complex reactions involving competitive adsorptions of multiple intermediates.

Electrocatalytic Refinery of Biomass-Based 5-Hydroxymethylfurfural to Fine Chemicals

“…(b) Comparison of the cell voltages required to drive different current densities for HOR//HER electrolysis and OER//HER electrolysis. Reproduced from ref . Copyright 2022 American Chemical Society.…”

“…LDHs can be modified as ideal dual-functional electrocatalysts, enabling the coupling of the HOR and the HER under alkaline conditions. Zeng et al . recently reported a “new” class of catalysts consisting of Rh-O 5 /Ni­(Fe) atomic sites incorporated into nanoporous mesh-type, layered double hydroxides, which reportedly exhibit the highest level among catalysts reported.…”

Single-Atom Cr–N4 Sites with High Oxophilicity Interfaced with Pt Atomic Clusters for Practical Alkaline Hydrogen Evolution Catalysis

“…Electrochemical water splitting has been widely recognized as a promising approach to generate hydrogen with zero emissions. − In general, water electrolysis can be operated in either acidic or alkaline media. In view of the fact that most oxygen-evolution catalysts at the anode are subjected to corrosion in acid, alkaline anion-exchange-membrane water electrolysis (AEMWE) is more competitive and widely applied in industry for scalable hydrogen production. ,, Despite intensive investigations in cost-effective alternative catalysts over the past several decades, the most efficient catalysts for the hydrogen evolution reaction (HER) in AEMWE are still based on Pt, inherently owing to its near-optimal hydrogen absorption energy. − However, the conventional Pt/C catalysts are suffering from high cost, low HER mass activity (especially in alkaline media), , and insufficient stability, which pose big obstacles for the large-scale rollout of Pt catalysts in AEMWE. , …”

Atomic Modulation of Single Dispersed Ir Species on Self-Supported NiFe Layered Double Hydroxides for Efficient Electrocatalytic Overall Water Splitting

“…19 Additionally, the sluggish HER kinetics of NiFe-LDH can be accelerated by the same strategy. 20 Wang et al reported that the Cl-coordinated Pt single site decreased the energy barrier of water dissociation and optimized the H binding energy, accelerating the HER kinetics. 21 As a platinumgroup metal, iridium (Ir), especially the Ir single atoms, are believed to significantly improve the OER activity by regulating the adsorption of reaction intermediates.…”

“…For example, Zhang et al proposed that the interaction of Au single atoms and NiFe-LDH regulated the charge density of active Fe sites, which prompted the adsorption of hydroxide and decreased the energy barrier of the formation from *O to *OOH, thus enhancing the OER performance . Additionally, the sluggish HER kinetics of NiFe-LDH can be accelerated by the same strategy . Wang et al reported that the Cl-coordinated Pt single site decreased the energy barrier of water dissociation and optimized the H binding energy, accelerating the HER kinetics .…”