Dr Yiyang Li

Abstract:

Herein, a straightforward method is proposed for the selective conversion of CO2 and H2 into propane. This is achieved in a 50 mL batch reactor (45 bar and 230–270 °C) by combining a RhIn/MgOx catalyst with highly acidic ZSM-5 and co-feeding benzene. The addition of 50 mg of benzene is found to be optimal to skew the hydrocarbon selectivity away from C2 and C4–6 towards C3, while maintaining high conversion (>60%) and low CO selectivity (27%) during the 10-hour reaction. Benzene promotes the formation of propane by enhancing the aromatic hydrocarbon pool cycle at the expense of the olefinic cycle. Benzene achieves this by “grabbing” in-situ produced methanol and preventing the over-methylation of aliphatics. In turn, the generated polymethyl benzene species undergo a paring mechanism to produce propylene, which is converted to propane. The role of benzene is elucidated through comprehensive characterisations and extensive control experiments.

Abstract:

Professor Shik Chi Edman Tsang (1962–2025) made sustained and influential contributions to heterogeneous catalysis through a distinctive approach that integrates nanostructure design, advanced characterization, and mechanistic understanding. This Account, written by his former students, highlights the key research themes that defined his scientific career, centered on the principle that catalytic function arises from the controlled interplay of structure, electronic properties, and interfaces at the atomic scale. Early studies on carbon nanostructures and supported nanoparticles established the importance of direct structural observation in understanding catalytic behavior. These foundations evolved into systematic strategies for nanostructure-controlled catalysis. A central theme of Tsang’s work is the role of interfaces and local environment in governing reaction pathways. These principles are exemplified in catalytic processes relevant to energy and sustainability, including hydrogen evolution, CO2 hydrogenation, ammonia synthesis and decomposition, and biomass and plastic conversion. Tsang’s contributions also extend to electrocatalysis and photocatalysis, where atomic-scale design is combined with external driving forces, such as electrical bias, light, and thermal energy. In parallel, the integration of advanced characterization techniques, particularly synchrotron-based methods and electron microscopy, has enabled direct observation of active sites and their evolution under working conditions. Importantly, his work bridges fundamental science and practical application, demonstrating how atomic-level catalyst design can inform scalable technologies for sustainable energy and chemical production.

Abstract:

Developing earth‐abundant electrocatalysts that rival the commercial platinum/carbon catalyst for the hydrogen evolution reaction (HER) remains a central challenge in renewable‐energy conversion. Here, we reveal an electrochemically induced, in situ phase transformation in a Ru‐MgO catalyst that leads to true active material during operation. Under acidic HER conditions, nominal 20 wt.% Ru nanoparticles supported on polar MgO(111) nanocrystals undergo a topotactic hydrolysis to Ru‐Mg(OH)2(001), generating an ordered hydroxide layer that serves as a highly conductive proton‐hopping network. After activation, the catalyst delivers performance comparable to commercial Pt/C under identical conditions, matching the current density of −1.1 V and surpassing it by approximately 10% at −2.3 V. Operando synchrotron X‐ray diffraction combined with ex situ characterization techniques directly captures this transformation, while density‐functional theory calculations reveal that water‐assisted Grotthuss proton transfer across the hydroxide requires only a 0.10 eV energy barrier. These findings establish electrochemically driven oxide‐to‐hydroxide conversion as a new design principle for creating low‐Pt or Pt‐free HER electrocatalysts with intrinsically fast proton transport.

Abstract:

Photocatalytic water splitting is a promising method for green hydrogen production. Great progress has been made in photocatalyst activity after decades of study. Cationic doping is one of the most extensively studied photocatalyst optimization strategies. Diverse findings, both positive and negative effects, have been reported, reflecting the complexity of the system. Thus, a deep understanding of both the fundamentals and current progress is essential for the rational exploration and development of this strategy. In this Review , we start by providing a brief introduction to the principles of photocatalytic water splitting and the evaluation indices of photocatalytic efficiency. Following that, we present the fundamentals of cationic doping, with special attention to the underlying thermodynamics and its modification of the structure and electronic structure of metal oxide photocatalysts. Building on this basis, we highlight recent progress in understanding how cationic doping affects fundamental steps in photocatalytic water splitting, with a focus on light absorption and charge transport. Finally, we summarize the current challenges and research gaps in the field.

Abstract:

The catalytic decomposition of ammonia under mild conditions is a promising route for green hydrogen production. However, conventional dissociative ammonia decomposition pathways over metal sites are suffering from the Brønsted−Evans−Polanyi (BEP) constraint which establishes an inverse correlation between atomic N binding energy and the N-H bond dissociation energy. Herein, we report a ruthenium-supported nitrogen-doped cerium oxide (Ru/N-CeO2) catalyst that breaks this limitation and exhibits significantly enhanced catalytic activity compared to its undoped counterpart. Furthermore, we reveal that N dopants can act as independent active sites, enabling an associative mechanism distinct from the conventional Ru-driven pathway. Comprehensive isotopic labelling experiments together with computational techniques elucidate the reaction mechanism over the N site and reveal a distinct correlation between the location of the active site and catalytic activity. The proximal N site exhibits the highest activity, challenging the conventional view that activity is dominated by metal–support interfacial sites. While N doping is a commonly used approach for surface modification, our findings show that it can also alter the reaction mechanism by introducing new active sites. These insights offer valuable guidance for the rational design of catalytic supports in ammonia decomposition and open new directions for catalytic systems limited by scaling relationships in heterogenous catalysis.