Hetero-nanostructured metal oxide-based hybrid photocatalysts for enhanced photoelectrochemical water splitting – A review

Global energy and environmental crises are among the most pressing challenges facing humankind. To overcome these challenges, recent years have seen an upsurge of interest in the development and production of renewable chemical fuels as alternatives to the nonrenewable and high-polluting fossil fuels. Photocatalysis, photoelectrocatalysis, and electrocatalysis provide promising avenues for sustainable energy conversion. Single- and dual-component catalytic systems based on nanomaterials have been intensively studied for decades, but their intrinsic weaknesses hamper their practical applications. Multicomponent nanomaterial-based systems, consisting of three or more components with at least one component in the nanoscale, have recently emerged. The multiple components are integrated together to create synergistic effects and hence overcome the limitation for outperformance. Such higher-efficiency systems based on nanomaterials will potentially bring an additional benefit in balance-of-system costs if they exclude the use of noble metals, considering the expense and sustainability. It is therefore timely to review the research in this field, providing guidance in the development of noble-metal-free multicomponent nanointegration for sustainable energy conversion. In this work, we first recall the fundamentals of catalysis by nanomaterials, multicomponent nanointegration, and reactor configuration for water splitting, CO2 reduction, and N-2 reduction. We then systematically review and discuss recent advances in multicomponent-based photocatalytic, photo-electrochemical, and electrochemical systems based on nanomaterials. On the basis of these systems, we further laterally evaluate different multicomponent integration strategies and highlight their impacts on catalytic activity, performance stability, and product selectivity. Finally, we provide conclusions and future prospects for multicomponent nanointegration. This work offers comprehensive insights into the development of cost-competitive multicomponent nanomaterial-based systems for sustainable energy-conversion technologies and assists researchers working toward addressing the global challenges in energy and the environment.

Noble-Metal-Free Multicomponent Nanointegration for Sustainable Energy Conversion.

The current rapid industrial development causes both a heavy reliance on non-renewable energy and a dramatic increase in atmospheric CO2 concentration, which in turn lead to severe energy and environmental crises. Utilizing the abundant solar energy to convert CO2 into usable or storable energy resources is considered to be a promising strategy to reverse the preceding challenges. Among studied formulations, earth-abundant one-dimensional (1D) copper-based photocatalysts, such as copper oxide, cuprous oxide and cuprous sulfide, featuring efficient visible light harvesting, facile CO2 adsorption and directional long-distance electron transfer assisted by the high length-to-diameter ratio of the 1D geometry, are ideal platforms to support suitable co-catalysts for the construction of various 1D copper-based heterostructures for CO2 photoreduction with enhanced photoactivity and photostability. This review will concisely recap the recent progress in synthetic preparation of different 1D copper-based nanomaterials with controllable structure, interface and morphology, particularly highlighting the application of 1D copped-based heterostructures for CO2 photoreduction via different mechanisms (e.g., controllable band alignments and multi-step electron flow) to value-added chemicals and fuels. Finally, some personal perspectives into future directions and challenges on rational design of highly efficient 1D copper-based composite materials for artificial CO2 reduction are presented, and are expected to promote the rapid progress of this dynamic research area.

One-dimensional copper-based heterostructures toward photo-driven reduction of CO2 to sustainable fuels and feedstocks

The conversion of solar energy into fuels is an attractive prospect for storing renewable energy, and photoelectrochemical technology represents a pathway by which solar fuels might be realized. Ideally, cost-effective photoelectrodes efficiently and stably drive anodic and/or cathodic half-reactions. However, no photoelectrode satisfies all the harsh requirements of practical applications, mainly involving high conversion efficiency and good stability. Narrow-gap semiconductor-based photoelectrodes have recently generated a great deal of interest because of their high conversion efficiency. The possible modification of the efficiency and stability using various structural engineering strategies has been largely responsible for the rapid growth of interest in these photoelectrodes. In this review, we aim to present the advances in the efficiency and stability of narrow-gap semiconductor-based photoelectrodes on three levels: fundamental bottlenecks, existing solution strategies, and applications.

Yu-Chen Chang

Papers

Facile synthesis of ZnO nanoparticles on carol-like Cu2O nanowires for photoelectrochemical hydrogen generation