Photoreforming is a process that harnesses the redox ability of photocatalysts upon illumination, to simultaneously drive the reduction of H⁺ into hydrogen gas and oxidation of organic compounds. Over the past few decades, significant effort has been devoted to improving the photocatalytic hydrogen evolution efficiency, while substantially less focus has been directed towards the oxidation reactions. More recently, the realization of the potential for simultaneous hydrogen production with value-added organics has inspired researchers to use photooxidation pathways to tune the selectivity of oxidized products. As a distinct benefit, the less energetically demanding organic reforming is highly favorable when compared to the slow kinetics of oxygen evolution which negates the need for expensive and/or harmful hole scavengers. Photocatalyst modifications, such as secondary component deposition, doping, defect, phase and morphology engineering, have been the main strategies adopted to tune the photooxidation pathways and oxidation products. Direct control of the process conditions, including pH, temperature and reactant concentration, and favorable reactor designs can further improve the selectivity towards desired products. While other published reviews focus on the types of photocatalysts or feedstocks used to enhance the hydrogen evolution efficiency, this review highlights the importance of controlling the selectivity of the photoreforming reaction, particularly as an alternative path for waste abatement or valorization for industry. This review links the strategies used to improve the selectivity of photoreforming of organic waste into high-value and desirable chemicals, as well as offers an outlook on the future research direction required to deliver highly selective photocatalyst. A holistic strategy that comprises photocatalyst and system designs, appropriate characterizations and implementation of artificial intelligence has also been proposed and discussed to further aid establishment of the structure–mechanism–function relationship, thereby accelerating the discovery of optimum selective photoreforming systems.

Graphene edges exhibit a highly localized density of states that result in increased reactivity compared to its basal plane. However, exploiting this increased reactivity to anchor and tune the electronic states of single atom catalysts (SACs) remains elusive. To investigate this, a method to anchor Pt SACs with ultra‐low mass loadings at the edges of edge‐rich vertically aligned graphene (as low as 0.71 µg Pt cm^–2) is developed. Angle‐dependent X‐ray absorption spectroscopy and density‐functional theory calculations reveal that edge‐anchored Pt SACs has a robust coupling with the π‐electrons of graphene. This interaction results in a higher occupancy of the Pt 5d orbital, shifting the d‐band center toward the Fermi level, improving the adsorption of *H for the hydrogen evolution reaction (HER). Pt primarily coordinated to the graphene edge shows improved alkaline HER performance compared to Pt coordinated in mixed environments (turnover frequencies of 22.6 and 10.9 s^–1 at an overpotential of 150 mV, respectively). This work demonstrates an effective route to engineering the coordination environment of Pt SACs by using the graphene edge for enhanced energy conversion reactions.

MXenes, due to their tailorable chemistry and favourable physical properties, have great promise in electrocatalytic energy conversion reactions. To exploit fully their enormous potential, further advances specific to electrocatalysis revolving around their performance, stability, compositional discovery and synthesis are required. The most recent advances in these aspects are discussed in detail: surface functional and stoichiometric modifications which can improve performance, Pourbaix stability related to their electrocatalytic operating conditions, density functional theory and advances in machine learning for their discovery, and prospects in large scale synthesis and solution processing techniques to produce membrane electrode assemblies and integrated electrodes. This Review provides a perspective that is complemented by new density functional theory calculations which show how these recent advances in MXene material design are paving the way for effective electrocatalysts required for the transition to integrated renewable energy systems.

A novel oxygen reduction reaction (ORR) electrode comprising isolated Co atom decorated vertically aligned graphene nanosheets is designed, which can enable the most energy-efficient, rapid acidic H ₂ O ₂ production in a flow-cell reactor.