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Far-infrared functional nanocomposites were prepared by the co-precipitation method using natural tourmaline $({\mathrm{\text{XY}}}_3{\mathrm{\text{Z}}}_6{\mathrm{\text{Si}}}_6{\mathrm{\text{O}}}_{18}{({\mathrm{\text{BO}}}_3)}_3{\mathrm{\text{V}}}_3\mathrm{\text{W}}$, where $\mathrm{\text{X}}$ is ${\mathrm{\text{Na}}}^{+}$, ${\mathrm{\text{Ca}}}^{2+}$, ${\mathrm{\text{K}}}^{+}$, or vacancy; $\mathrm{\text{Y}}$ is ${\mathrm{\text{Mg}}}^{2+}$, ${\mathrm{\text{Fe}}}^{2+}$, ${\mathrm{\text{Mn}}}^{2+}$, ${\mathrm{\text{Al}}}^{3+}$, ${\mathrm{\text{Fe}}}^{3+}$, ${\mathrm{\text{Mn}}}^{3+}$, ${\mathrm{\text{Cr}}}^{3+}$, ${\mathrm{\text{Li}}}^{+}$, or ${\mathrm{\text{Ti}}}^{4+}$; $\mathrm{\text{Z}}$ is ${\mathrm{\text{Al}}}^{3+}$, ${\mathrm{\text{Mg}}}^{2+}$, ${\mathrm{\text{Cr}}}^{3+}$, or ${\mathrm{\text{V}}}^{3+}$; $\mathrm{\text{V}}$ is ${\mathrm{\text{O}}}^{2-}$, ${\mathrm{\text{OH}}}^{-}$; and $\mathrm{\text{W}}$ is ${\mathrm{\text{O}}}^{2-}$, ${\mathrm{\text{OH}}}^{-}$, or ${\mathrm{\text{F}}}^{-})$ powders, ammonium cerium(IV) nitrate and zirconium(IV) nitrate pentahydrate as raw materials. The reference sample, tourmaline modified with ammonium cerium(IV) nitrate alone was also prepared by a similar precipitation route. The results of Fourier transform infrared spectroscopy show that tourmaline modified with Ce and Zr has a better far-infrared emission property than tourmaline modified with Ce alone. Through characterization by transmission electron microscopy (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS), the mechanism for oxygen evolution during the heat process in the two composite materials was systematically studied. The XPS spectra show that ${\mathrm{\text{Fe}}}^{3+}$ ratio inside tourmaline modified with Ce alone can be raised by doping Zr. Moreover, it is showed that there is a higher ${\mathrm{\text{Ce}}}^{3+}$ ratio inside the tourmaline modified with Ce and Zr than tourmaline modified with Ce alone. In addition, XRD results indicate the formation of ${\mathrm{\text{CeO}}}_2$ and ${\mathrm{\text{Ce}}}_{1-x}{\mathrm{\text{Zr}}}_x{\mathrm{\text{O}}}_2$ crystallites during the heat treatment and further TEM observations show they exist as nanoparticles on the surface of tourmaline powders. Based on these results, we attribute the improved far-infrared emission properties of Ce–Zr doped tourmaline to the enhanced unit cell shrinkage of the tourmaline arisen from much more oxidation of ${\mathrm{\text{Fe}}}^{2+}$ to ${\mathrm{\text{Fe}}}^{3+}$ inside the tourmaline caused by the change in the catalyst redox properties of ${\mathrm{\text{CeO}}}_2$ brought about by doping with ${\mathrm{\text{Zr}}}^{4+}$. In all samples, tourmaline modified with 7.14 wt.% Ce and 1.86 wt.% Zr calcined at 800${}^{\circ }$C for 5 h has the best far-infrared emission property with the maximum emissivity value of 98%.

Oxygen evolution reaction (OER) is of great importance in splitting water. However, the sluggish OER kinetics at the anode severely hinders the H₂ evolution at the cathode which is a crucial procedure for energy storage. Herein, we report the synthesis of a new OER catalyst of Co(OH)_x(WO${}_4{)}_y$via a one-step hydrothermal method, where the incorporation of WO${}_4^{2-}$ as a condenser greatly enhanced the electrocatalytic activity of Co(OH)₂ toward OER. Moreover, the introduction of mesoporous carbon (MC) further improves the electrocatalytic performance of Co(OH)_x(WO${}_4{)}_y$ by forming the nanocomposites of Co(OH)_x(WO${}_4{)}_y$/MC. The synergism between Co(OH)₂ and WO${}_4^{2-}$ and the synergistic catalytic effect of Co(OH)_x(WO${}_4{)}_y$ and MC majorly contributed to the apparently enhanced electrocatalysis of Co(OH)_x(WO${}_4{)}_y$/MC toward OER. This work provides an efficient strategy to improve the electrocatalytic activity of Co(OH)₂ by introducing WO${}_4^{2-}$ and forming nanocomposites between Co(OH)_x(WO${}_4{)}_y$ and MC for low-cost, convenient and highly efficient water oxidation.

The splitting of water into its constituent elements is an important solar fuels conversion reaction for the storage of renewable energy. For each of the half reactions of the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER), multiple protons and electrons must be coupled to avoid high-energy intermediates. To understand the mechanistic details of the PCET chemistry that underpins HER and OER, we have designed hangman porphyrin and corrole catalysts. In these hangman constructs, a pendant acid/base functionality within the secondary coordination sphere is "hung" above the macrocyclic redox platform on which substrate binds. The two critical thermodynamic properties of a PCET event, the redox potential and pK_a may be tuned with the macrocycle and hanging group, respectively. This review outlines the synthesis of these catalysts, as well as the examination of the PCET kinetics of hydrogen and oxygen evolution by the hangman catalysts. The insights provided by these systems provide a guide for the design of future HER and OER catalysts that use a secondary coordination sphere to manage PCET.

Development of high-performance nonprecious metal-based catalysts for oxygen evolution reaction (OER) is crucial to improve the efficiency of water electrolysis and photoelectrochemical water splitting for harvesting and storage of solar energy. Herein, Co–Fe phosphates and their composites with reduced graphene oxide (rGO) were prepared by a simple hydrothermal method, which then acted as oxygen evolution reaction catalysts. In 1.0 M KOH aqueous solution, the as-obtained optimal composite, Co–Fe phosphate/rGO, can catalyze oxygen evolution reaction with a very sharp onset potential and a small over-potential of 338mV to achieve a current density of 10mAcm${}^{-2}$. It was found that in these Co–Fe phosphates, the optimal Co:Fe ratio is 0.75:0.25. The excellent electrocatalytic performance of the Co–Fe phosphate/rGO composite would benefit from the synergistic effects between Fe and Co species, as well as rGO substrate providing conductive channels. The formed Co–Fe phosphate/rGO electrocatalysts can be the promising replacement of precious metal-based catalysts for more practical and cost-efficient water splitting.

The increasing energy crisis promotes the study on novel electrode materials with high performance for supercapacitive storage and energy conversion. Transition metal phosphates have been reported as a potential candidate due to the unique coordination and corresponding electronic structure. Herein, we adopted a facile method for preparing NaCoPO₄@C derived from a metal organic framework (MOF) as a bifunctional electrode. ZIF-67 was synthesized before a refluxing process with Na₂HPO₄ to form a precursor, which is transformed into the final product via calcination in different atmospheres. Specifically, the resultant NaCoPO₄@C exhibits a high specific capacitance of 1178.7Fg${}^{-1}$ at a current density of 1Ag${}^{-1}$ for a supercapacitor. An asymmetric supercapacitor (ASC) assembled with active carbon displays a high capacitance of 163.7Fg${}^{-1}$ at 1Ag${}^{-1}$. In addition, as an oxygen evolution reaction (OER) catalyst, the NaCoPO₄@C electrode requires only 299mV to drive a current density of 10mAcm${}^{-2}$. These results suggest that the rational design of MOF-derived NaCoPO₄@C provides a variety of practical applications in electrochemical energy conversion and storage.

Conversion of solar energy to useful chemicals has become necessary for finding solutions to energy and environmental issues. One of the means is to use of solar energy for the reduction of water to generate hydrogen or for the reduction of CO${}_{\mathrm{\text{2}}}$ to useful chemicals. In spite of substantial effort, the discovery of stable and efficient photocatalysts remains a challenge, although some encouraging results have been reported. In this article, we provide a brief perspective of the current status of solar water splitting and reduction of CO${}_{\mathrm{\text{2}}}$.