Surface Strategies for Particulate Photocatalysts toward Artificial Photosynthesis

Abstract

Particulate photocatalyst-based artificial photosynthesis using water as an electron donor offers a renewable and scalable way to produce solar fuels. In constructing artificial photosynthesis systems, strategies based on modifying the semiconductor surface can remarkably influence the adsorption and activation abilities of ions/molecules, the control of the reactions involved, and the efficiencies of charge separation and catalytic conversion. In this review, three common ways of improving the photocatalytic performance of overall water splitting or CO 2 reduction are summarized: (1) surface regulation by crystalline phase, crystal facet, and surface defect; (2) surface functionalization through the introduction of co-catalysts and/or a ''photo-inert'' metal oxide; (3) surface assembly with another semiconductor photocatalyst to form a heterostructure or an all-solid-state Z-scheme system. Challenges and future trends in the development of efficient artificial photosynthesis systems are also discussed briefly.

Rationally designed transition metal hydroxide nanosheet arrays on graphene for artificial CO2 reduction

“…A rtificial photoreduction of carbon dioxide (CO 2 ) into useful chemical feedstocks offers a promising and sustainable long term solution to the issues of increasing energy demands and climate change [1][2][3][4][5][6] . Nevertheless, there is still a long way to achieve efficient and selective photocatalytic CO 2 reduction, especially in diluted CO 2 , which is primarily because of the low CO 2 adsorption, high recombination rate of charge carriers in photocatalysts, concealed active sites, and the competing H 2 evolution reaction [7][8][9][10][11] . To overcome these limitations, rational construction of hybrid photocatalytic systems, in which photosensitizers and cocatalysts operate in a harmonious manner, has arisen as a promising approach [12][13][14][15][16] .…”

Research advances towards large-scale solar hydrogen production from water

“…For OER, oxides of Mn, Co, Ni, Ru, and Ir are commonly used as the co-catalyst. 47 The synergistic effect of applying both HER and OER co-catalysts to the same photocatalytic system has been demonstrated, affording up to twofold increase in AQE compared with using one co-catalyst. [54][55] With appropriate alignment between the band energy of the light absorber and the co-catalyst, the latter acts as an electron trap to suppress recombination and increase quantum efficiency.…”

“…[45][46] On the other hand, recombination caused by presence of defects including lattice dislocation, interstitial filling, vacancies, and surface states can be suppressed by increasing the crystallinity of the photocatalyst and excluding contaminants. 47 Appropriate annealing, for example, is desirable in this regard. 48 Alternatively, the photocatalyst can be prepared in the form of nanoparticles to shorten the diffusion pathways of the charge carriers and hence their probability of recombination, as has been commonly carried out.…”

“…For example, Pt and other platinum-group metals are well known for their low HER overpotential and most frequently adopted as the HER co-catalyst. 47 In recent years novel materials based on earth-abundant elements including first-row transition metal phosphides 51 , chalcogenides 52 , and biomimetic molecular catalysts 53 for this purpose have gained increasing attention. For OER, oxides of Mn, Co, Ni, Ru, and Ir are commonly used as the co-catalyst.…”

Metal selenide photocatalysts for visible-light-driven Z-scheme pure water splitting

“…16 One possible means to apply selenides for overall water splitting is to use them as hydrogen evolution photocatalysts (HEPs) to construct a Z-scheme process together with other oxygen evolution photocatalysts (OEPs), but how to efficiently consume photogenerated holes from the selenides before their self-oxidization remains a key issue. [17][18][19][20] Recently, our group has developed a particulate photocatalyst sheet system for Z-scheme pure water splitting, in which the HEP and OEP are bridged by a conductive layer that transfers electrons from the OEP to the HEP. 21 Notably, these three components are integrated into one composite having low interfacial resistance, enabling efficient charge transfer and recombination among them.…”